KR20070091599A - Watermelon with improved processing qualities - Google Patents

Abstract

A watermelon plant that produces fruit having (i) ultra-firm flesh and/or liquid-retaining flesh and (ii) soluble solids of at least about 6 brix.

Description

WATERMELON WITH IMPROVED PROCESSING QUALITIES

Cross Reference to Related Applications

This application claims the priority of Provisional Application No. 60 / 584,964, filed Jul. 2, 2004, and Utility Model Application No. 10 / 972,190, filed October 22, 2004, incorporated herein by reference.

Field of technology

The present invention relates to watermelon breeding and watermelon genetic improvement. More specifically, the present invention provides a diploid for producing watermelon that (i) has an extremely hard flesh and / or liquid retaining flesh, and (ii) a sugary sugar at maturity, Tetraploid and triploid watermelon seeds and plants.

Description of Related Technologies

Watermelon ( Citrullus lanatus ) is an important commercial crop of the Cucurbitaceae family, which includes a variety of varieties. The fruits of these species differ in color, sugar and other properties. For example, different kinds of watermelons display various colors on the outer shell. In addition, the color of the edible tissue varies from red to yellow in various shades. Watermelon also differs in sugar or brix that can be assessed by measuring the total soluble solids using a refractometer. Because sugar is particularly important to consumers, the US Department of Agriculture has established a fruit quality standard based on the Briggs level (US Standard for Watermelon Grades, US Department of Agriculture (1978)). According to this standard, an edible portion having a value of 8 brix or more is judged to be "good", while an edible portion having a value of 10 brix or more is determined to be "very good".

In addition, consumers have the choice between seedless watermelon or seedless watermelon. Unlike the flesh color caused by changing the genetic loci, the difference between seeded and seedless species is usually caused by anthropogenic behavior that creates crosses that change ploidy levels. Similar to humans, watermelons are natural diploids with paired chromosomes. Many meals, including watermelon, can exist as tetraploids by performing a replica of their complete set of chromosomes. It is unusual for watermelons to form tetraploids naturally, but this process can be routinely produced in the laboratory using cell biology techniques. The tetraploid parents can then be crossed with the diploid parents to make triploid seeds, which in turn can produce plants with seedless fruit. In particular, seed production in the fruits of triploid plants fails because of differences in ploidy levels, resulting in seedless fruits. Many commercial species are triplets without seeds.

In addition, the fruits of different drainage plants differ in the hardness of the pulp. Diploid strains typically have the lowest fruit pulp rigidity level. The reason for this is not clear, but the process of transforming a diploid line into a tetraploid line correlates with the harder fruit pulp. In other words, tetraploid lines usually have a harder fruit flesh than diploid lines. Triplots obtained by crosses between tetraploids and diploids typically have intermediate levels in the firmness of the flesh.

In addition to consumer preferences for color, sugar and seed, consumer demand is increasing in fresh produce trades for products that combine quality and convenience. Examples of agricultural products that meet these criteria are packaged baby carrots, broccoli and cauliflower and packaged leafy crops such as lettuce and spinach. Similarly, there is a need for mature cut fruits such as watermelon, melon, pineapple, papaya and kiwi. An increasing portion of the watermelon retail sales are cut fruits that are exhibited in large pieces with peeled or cut into smaller pieces without shells, which are provided to consumers in plastic food containers. The industrial term for these agricultural products is "minimally processed." In 1998, Perkins-Veazie et al. ((1998) Hortscience 33: 605) estimated that 10% of the watermelon retail market was processed to a minimum.

The advantage of such a cut fruit display is that the consumer can visually check the quality of the fruit and, in particular, can determine whether the fruit is ripe and suitable for purchase. Occasionally immature fruits will be non-pigmented and too ripe fruits will show signs of decay. Moreover, these products provide convenience to the consumer.

A disadvantage for farmers in providing a minimum amount of processed watermelon products is that the cut fruits have a short shelf life. Studies have shown that products processed in minimal quantities have a shelf life of up to 2-3 days (same literature; Wehner et al .: Watermelon: features, production and marketing. Maynard, editor. ASHS Press, Alexandria, VA. , 2001).

Watermelons currently available typically exhibit a rapid deterioration after being cut. Fruit cuttings cause rot, which is observed to reced fruit flesh. In addition, deterioration is evidenced by liquid leakage, and in some other species the flesh of freshly cut watermelon quickly becomes unattractive to the consumer. The rapid deterioration of the cut watermelon limits retailers both time and space. Since the cut fruit has a short shelf life, the retailer typically has to perform processing at the place of retail. Moreover, the retailer should inspect the products frequently to ensure that they dispose of the altered products.

Unlike the sugar standards established by the US Department of Agriculture, there are no industrial standards describing the hardening of the edible portion of watermelon. Thus, in use, "very firm flesh" (Zhang et al., USPTO Application No. 20040060085) from "firm" and "crisp" (Erma Zaden catalog description for Gil104 and Erma12 species); Extensive descriptions have been made up to 20030217394 and the Seminis watermelon catalog for the variant Cooperstown. Seminis offers "excellent crispness", "firm flesh" and "crisp juicy flesh" varieties of Fenway and Royal Star, respectively. ) And Sentinel. Furthermore, the Rogers Seed Company is an "exceptionally firm", with Tri-X Brand 626 and "firm texture" and "crispness". As a result, the company is advertising Tri-X Brand 313.

While the advertising terminology used to describe the watermelon pulp is very variable, scientific reports using quantitative measurements suggest that typical commercial germplasm is significantly lower than the watermelon of the present invention. Show that it has For example, Roberts et al. (2004 report from Watermelon Research and Development Working Group. 24 ^th Annual Metting, Tulsa, OK) use a penetrometer to measure the amount of resistance to produce a broad range of The pulp hardness was measured. Data was reported in Newtons, an international system of measurement terms. In order to compare Applicants' permeability measurements, Applicants converted Robert data to pound force (lbf) using the following equation: 1 lbf = 4,448 Newtons. Robert reports a watermelon pulp rigidity range of about 1.4 to 3.4 lbf. One of the lines analyzed is Rogers Seed Company Line Tree-X Brand 313. As mentioned above, Rogers Seed Company advertises these strains as having a "firm" pulp. Robert measured that the Tri-X Brand 313 had a pulp toughness of 10.84 Newtons, which translates to about 2.4 lbf. Applicants also tested the pulp hardness of the Tri-X brand 313 using a permeometer (QA Supplies, Norfolk, Virginia (Model FT011)) with a diameter of 8 mm. In this way, Tri-X brand 313 was determined to have a fleshy hardness of 1.4 lbf (Table 1). Since Robert did not report the size of the penetrometer probes used, Applicants could not directly compare their data with Robert's data. For at least Tri-X Brand 313, a greater than 77% greater value as measured by Robert et al. Compared to the protocol described herein may be a result of other methodologies, in particular the use of a penetrometer probe of different sizes Can be. Although the applicants of the present invention used an 8 mm sized probe, other commonly used penetrometers also have a diameter of 11 mm, since the permeometer area is about 73% larger for an 11 mm probe compared to an 8 mm probe. This may be the reason for the different figures.

In addition, Schultis and Thommp (Watermelon Research and Development Working Group. 24 ^th Annual Meeting. 2004 report from Tulsa, OK) examined the watermelon pulp rigidity. Although these authors used a different model of penetrometer than those used by the applicants, they used probes of very similar size with a diameter of 5/16 "or about 8 mm. Schultis and Thomson, X 313 reports a pulpy hardening value between 1.4 and 1.7, similar to the Applicants' measurements shown in Table 1. However, the authors describe this hard data in pounds per square inch. However, the units provided in the Schultis and Thomson report must be pound-force, which is only 0.15 pound-force when using a 5/16 "probe at 1.4 pounds / square inch.

Maynard and Sidoti (2003 GCREC Research Report BRA-2003: Florida Univ., Gulf Coast Research and Education Center, Bradenton, FL) report additional findings of hardening fruit pulp in commercial watermelon systems. It was. In this study, the authors used a larger sized probe with a diameter of 7/11 "or about 11 mm, a different model of permeability than the ones Applicants used in the method described here. Their rigid data ranged from 1.8 to 3.0 pounds / In addition to the Schultis and Thomson report, applicants believed that these authors used incorrect units in their hard readings, assuming that these data are substantially pound force units, the data here The results obtained using the method described in Fig. 3 are well compared, for example, the measure of the hardness of the Menad and Sisotti of the phylogenetic tree-X 313 was 2.6. If you adjust this number to calibrate it, the new value is 1.35, which is the applicant's side of this system. Almost identical to politics (Table 1) On the other hand, assuming that the data are reported accurately in pounds per square inch, a value of 2.6 pounds / square inch based on a 7/16 "probe reads 0.39 lbf. Will be. The Tri-X 313 line should have a much higher reading than the above 0.39 lbf, further evidence that such units are inconsistent with the methodology that has been reported in prior art.

In addition, Leskovar et al. (2004) J. Horticultural Science and Biotechnology 79: 75-81 report the firmness of watermelons. Although this method uses different measurement protocols, the authors describe their methods in detail, and it is possible to convert the data for comparison with the data described here. After conversion to the same units, the range of germplasm analyzed had fruit rigidity between 0.9 lbf and 1.51 lbf.

Although the measurements of the prior art can be confusing, it is evident that commercial watermelon strains produced prior to the present invention certainly have fruit rigidity of less than 3 lbf. Furthermore, as described in Example 4, the fruits of these commercial watermelon strains, once cut, produce a significant liquid spill. Thus, the present invention addresses the need in the marketplace for watermelon strains that produce fruits with a longer shelf life in processing. In particular, the watermelon of the present invention has (i) an extremely hard pulp that avoids the problem of excessively falling off the cut fruit and / or (ii) a liquid retaining pulp that delays the deterioration of the cut fruit due to liquid leakage. Furthermore, these fruits have quality characteristics as desired by the consumer in sweetness and taste, and provide retailers with flexibility for additional shelf life after the fruits are processed and where they are processed.

Summary of the Invention

The present invention is resistant to at least 3.0 pound force (lbf) (by means of the measurement method defined herein) and, at maturity, produces a single watermelon inbred line that produces an extremely hard edible fruit. And hybrid variants. In addition to the novel extremely hard flesh phenotype, these fruits satisfy more than 6 brixes (by the measuring method defined herein), which is the market requirement for sugar content for edible tissue.

The watermelon of the present invention is preferably a diploid and tetraploid suburb, which is resistant to at least 3.5 lbf and produces an extremely hard pulp that, when mature, has a sweet taste and also at least 4, 5, 6 and even 8 lbf. Lines that produce extremely hard pulp that is resistant to and sweet at maturity are contemplated by the present invention. In addition, many watermelon plants grown outdoors are provided by the present invention.

Any diploid or tetraploid inbred system having an extremely hard pulp prepared as taught by the present invention can deliver such an extremely hard pulp phenotype in hybridization. In addition to having extremely hard pulp at maturity, the watermelons of the invention can be developed into evenly colored fruit pulp (red, yellow or orange). Moreover, at maturity, fruits from these suburbs and hybrids will meet or exceed the industrial standard for at least good (at least about 8 brixes) and preferably very good (at least about 10 brixes) sugars. Can be.

The present invention also provides a method of producing hybrid watermelon seeds, which includes crossing a suburban watermelon plant with a second watermelon plant and harvesting the resulting hybrid watermelon seed, as well as growing the resulting hybrid watermelon seed. Provides hybrid watermelon plants.

Furthermore, the present invention hybridizes watermelon species having a sugar level that at least meets industry standards with low sugar watermelon species having extremely hard flesh; Performing at least one back cross with a species having a sugar level of at least meeting industrial standards; Provide a method of producing an extremely hard watermelon plant comprising the steps of performing one or more self pollinations of a compost (or regressive compost) product having at least an extremely hard pulp and sugar content that meets industry standards. do. In the method of the present invention, watermelon plants of USDA collection number PI296341 can be used as watermelons having extremely hard flesh.

Also contemplated are watermelons derived from extremely hard watermelon and watermelon pulp. It is preferably watermelon plants that produce fruit weighing at least about 1.5 kg, and more preferably fruit weighing at least about 3.0 kg. In a more preferred embodiment, the watermelon plant produces at least about 4.5 kg of fruit, and in yet another preferred embodiment, the plant produces at least about 6.0 kg of fruit.

The invention also relates to watermelon plants with soluble solids and hard fleshy properties of plants produced from seed deposited as deposit No. NCIMB 41230, dated July 1, 2004, as well as seeds, pollen, Egg cells and other vegetative tissues or watermelon plants regenerated from such tissues are provided.

The present invention also provides a watermelon plant having a liquid retaining pulp. As described in detail below, this liquid retention feature corresponds to the weight at which the cut watermelon pulp is lost over time. Watermelon plants are preferred in which the cut pulp from watermelon is lost to less than about 3.5% of its weight after being stored for 3 days at 4 ° C. Watermelon plants are more preferred where the chopped flesh loses less than about 3% of its weight after 3 days of storage at 4 ° C. Even more preferred is a watermelon plant, in which the chopped flesh loses less than about 2% of its weight after storage for 3 days at 4 ° C. In another preferred embodiment, the watermelon plant has a chopped pulp that loses less than about 1.5% by weight after three days of storage at 4 ° C. The retention of this liquid extends the shelf life of the processed watermelon.

A preferred embodiment is a good, extremely hard fleshy watermelon diploid suburb that produces a sweet fruit mature. Another preferred embodiment uses, as at least one parental system, either an extremely hard pulp diploid suburb or an extremely hard pulp diploid suburb which produces an extremely hard pulp and produces a mature fruit with good standard sweetness. It is a triplet hybrid made. In another preferred embodiment, the mature watermelon produced in diploid, tetraploid or triploid plants of the present invention develops a full red flesh color, has a sweet and good brix level.

In another preferred embodiment, the mature watermelons of the present invention exhibit a full yellow flesh color and excellent sweetness with extremely hard flesh. In another preferred embodiment, the mature watermelons of the present invention exhibit a full orange color and excellent sweetness with extremely hard flesh. In another preferred embodiment, the watermelon pulp from the fruits of the present invention remains extremely hard after being processed to a minimum (fresh cut fruit). This extremely rigid feature extends the shelf life of processed fruits.

In addition, the present invention is novel to produce triploid watermelon hybrids that produce sweet fruit mature fruits with diploid and tetraploid watermelon strains and extremely hard flesh (greater than 8 brixes and resistant to pressures of at least 4.0 lbf). It's about one way.

One step of the method involves mating a known watermelon strain or strain with a watermelon strain of the present invention having extremely hard pulp at maturity. The product of this hybridization is then self-pollinated to create a separate population. In successive generations, individuals isolated from the groups as having extremely hard pulp properties are subjected to a continuous cycle of selection and breeding, and the final result is a sweetness with extremely hard pulp. It is a new watermelon strain that produces mature fruit.

Other objects, features and advantages of the present invention will become apparent from the following detailed description. Since modifications and variations that fall within the scope of the invention may be apparent to those skilled in the art, it is to be understood that the detailed description and examples that describe preferred embodiments of the invention are merely a means of illustration.

1 is a graph illustrating the hardness of the third generation fruit pulp of the self-pollinated inbred watermelon plants of the present invention. Arrows indicate the average value of mature fruit firmness of the recurrent parent line. The shadow portion of the graph shows that 43% of these fruits have solid measurements at or above 4 lbf.

Figure 2 is a graph showing the weight loss after processing the processed fruit of the standard commercial watermelon species and the processed fruit of the watermelon of the present invention at 4 ℃. The weight loss is close to the amount of liquid leakage from the processed fruit.

Detailed description of the invention

The present invention provides a watermelon plant that produces (i) a pulp containing extremely hard pulp and / or liquid and (ii) a fruit having a sugar content of at least 6 brixes. Thus, the fruit of the present invention has improved processing quality, and the fruit remains significantly harder than the commercial watermelon strains of the prior art and / or retains juice even after cutting.

Justice

As used herein, the term “plant” refers to plant cells, plant protoplasts, plant cells of tissue culture from which watermelon can be regenerated, plant calli, plant clumps and pollen, flowers, Plant cells such as seeds, leaves, stems, and the like, or plant cells that are intact in parts of plants.

As used herein, “ploploid plants” are plants or transplanted plants derived from micro propagation from sowing diploid seeds or having two sets of chromosomes in somatic cells or doubling the haploid number. Means plants.

"Triploid plants" refers to plants or transplanted plants derived from micro propagation from sowing of triploid seeds or having three sets of chromosomes in somatic cells or three times the haploid number.

"Quadploid plants" means plants or transplanted plants derived from microploiding from sowing tetraploid seeds or having four sets of chromosomes or four times the haploid number in somatic cells.

The term “firm pulp” refers to the pulp of an edible watermelon when the hardness of the fruit is greater than about 1.5 lbf pressure but less than about 2.0 lbf when measured using a permeometer by the method described in Example 2. Botanically, the edible flesh of watermelon is placental tissue.

The term "ultra hard pulp" refers to a fruit hardening of about 3.0 lbf or more, as measured using a penetrometer by the methods described in Example 2, or produced by standard known varieties. It represents the flesh of harder edible watermelons than fruit. The extremely hard watermelon pulp has a fruit firmness of about 3.5 lbf.

The term “very hard pulp” refers to the pulp of an edible watermelon with fruit firmness greater than about 2.0 pound force but less than 3.0 pounds when measured using a permeometer by the methods described in Example 2. Indicates.

The term "liquid holding pulp" refers to loss of less than about 4% of the weight of watermelon after cutting and storage for 3 days at 4 ° C., or retains more liquid over time than fruits produced by standard known varieties. It shows the pulp of edible watermelon. Approximately 95% to 98% of the weight lost from the cut watermelon is estimated to be due to liquid leakage. Most of the remaining weight loss is from soluble solids such as sugars and acids. Thus, liquid loss can be estimated by measuring the weight loss percentage of the sliced watermelon over time.

A "penetrometer" is a device designed to measure force and is used here to measure fruit hardness. This provides a fast, easy and accurate way to determine fruit pulp and peel hardness. Applicants collected data reported here using a handheld permeometer to obtain three to five pressure readings from mature fruit. In particular, Applicants used a penetrometer model FT011 (QA Supplies, Norfolk, VA) with a probe of 8 mm or about 5/16 inches.

"Pound force" or "lbf" is a unit read by the penetrometer model FT011 and is used herein to represent readings measured using an 8 mm probe, unless otherwise stated.

The coloring of the watermelon peel, also referred to as the "shell pattern", can vary from light green, often referred to as gray, to very dark green, appearing medium to green, almost black. Moreover, the shells may have stripes of various designs typical in type and shape. Thus, the terms "tiger stripe", "mottle stripe", "dark mottle stripe" and the like are used to define various patterns.

As used herein, "L / W ratio" means the ratio obtained by taking the average length divided by the average width in watermelon and in any possible combination. This ratio can vary from 1: 1.2 to 2.2: 1.

The term “population” refers to a genetically heterogeneous population of plants that share what is derived from conventional parents.

As used herein, the term "variety" or "cultivar" refers to a group of similar plants that are distinguishable from other species within the same species by their genetic ancestry and performance.

"Backcross" refers to the process by which breeders cross a plant with one of its parental lines.

"Recurrent backcross" is a breeding strategy designed to restore the genetic composition of a line by successively decomposing one plant with one of the parental lines.

The term "soluble solids" refers to the percentage of solids found in the edible fruit. As used in the present invention, soluble solids are measured quantitatively with a refractometer as Brix%. When the bric is defined as the weight percent of sucrose, the refractometer mainly comprises sucrose units. If the soluble solids present in the aqueous solution are only sucrose, the sucrose units must provide substantial% sucrose. However, if other soluble solids are present, which is almost common, the reading is not equal to the% sucrose, but the total soluble solids in the sample is about the same. That is, although the brix is technically defined as weight percent sucrose, those skilled in the art can see that the weight percent of soluble solids obtained with the refractometer is almost similar to the weight percent sucrose and exhibits a precise sweetness. Thus, as measured by brix levels, the higher the soluble solids percentage, the higher the perceived sweetness of the fruit.

The US Department of Agriculture has established watermelon fruit quality standards based on Briggs levels (United States Standards for Grades of Watermelon, U.S. Department of Agriculture (1978)). According to these standards and as used herein, the edible portion of the fruit having a value of 8 brix or more indicates "excellent", while the edible portion of the fruit having a value of 10 brix or more represents "very good."

As used herein, "sugar" can be measured quantitatively as described above using a refractometer, or qualitatively by taste.

A "quantitative trait loci" or "QTL" is the position of a chromosome that encodes an allele that affects the expression of successively distributed phenotypes.

"Maturity" refers to the maturity of fruit development, indicating the optimum time for harvesting. Usually, growers who are skilled in the art harvest fruits at or substantially near the highest sweetness and flavor strength of the fruits. Maturity in watermelon is associated with changes in skin appearance, pulp color and sugar content.

The terms "homozygous" and "homozygosity" are genetic terms. When the same allele is present at the corresponding locus on homozygous chromosomes, that locus is said to be homozygous. Homozygosity typically refers to the extent to which a population is anchored to one or more loci.

A "hybrid" is a descendant of crosses between two genetically different individuals.

"Inbreeding" or "in-breeding" are substantially homozygous individuals or species.

"Introgress" is usually the process performed by breeders to introduce new features from non-cultivation to redeployment.

Typical Characteristics of Commercial Watermelons

Successful watermelon production depends on the attention of various cultivation methods. These include soil management such as special attention to proper fertilization; Crop settlement, such as adequate downtime; Weed control; Introduction of bees for plant pollination; if fruit is produced from triploid plants, a suitable pollen source for seedless (triploid) watermelon production; Water atmosphere; And infectious disease disaster management. Watermelon size and shape, skin color, thickness and toughness, seed size, color and number, flesh color, texture, sugar content and fruit flaw prevention are all important features that can be considered when choosing watermelon species. . Commercial seed companies typically provide growers with the opportunity to observe these features within their species' pilot compartments, and some agricultural colleges perform cultivation data analysis for local growers (Robert et al. (2004), Maynard and Sidotti (2003), Schultis and Thompson (2004) and Lescovar et al. (2004)).

Watermelon crops can be established from seeds or transplanted plants. Transplantation may be more common because it may lead to earlier crop harvesting compared to crops produced from direct sowing. Transplantation is desirable when growers want to grow seedless fruit crops. Transplantation helps to achieve rapid and complete plant entry, especially when seed seed is expensive, such as triploid seeds, which are at risk of direct sowing.

Watermelons are the only economically important gourds and plants with pinnatifid lobe leaves, and all other species have leaves in their entirety. Watermelon growth habits are moving vines. Stems are thin, hairy, hairy, grooved, and each knot has branched tendrils. The stems have a number of branches, up to 30 feet in length (Wener et al .: Watermelon: properties, production and marketing, Maynard, editor, ASHS Press, Alexandria VA 2001).

Watermelon breeders are challenging to anticipate changes in growth conditions, new pathogen attacks, and changing consumer preferences. Together with these initiatives, breeders will attempt to create new varieties that can meet the growing needs of growers, shippers, retailers and consumers. Thus, breeders are challenged to combine a variety of superior attributes to enable good growth, transport and uptake within a single genotype. Breeders recognize fruit size as an important feature. Fruit size is an important consideration because of the different market demands for special groups of subcontractors and consumers. Common categories are iceboxes (<12lb), small (12-18lb), medium (18-24lb), large (24-32lb), and large (> 32lb). Fruit size is inherited in a multigenic fashion involving an estimated 25 genes. Fruits are distributed from growers to retailers by owners, and the owners focus on specific weight categories, such as 18 to 24 lb with seeds and 14 to 18 lb without seeds. Although consumption has historically been in this size category, the market demand for new varieties of small fruit watermelon hybrids (with fruit weights of 3 to 9 lbs) tends to increase.

Fruit pulp hardening and liquid retention are other important properties. Consumers have a variety of texture preferences for watermelons, and the firmness of the flesh is a determinant of texture. In addition, pulp hardness is an important parameter that determines how long the cut fruit is sustainable in the retailer's display. Liquid retention is also important for consumer perception of watermelons processed in minimal amounts. Cut fruit shelf life studies are usually qualitative and follow the assessment when the fruits are “slimy” (Perkins-Veazie et al., 1998, Hortscience 33; 605). Quantitative assessment of cut fruit storage periods directly measures pulp hardness using a permeometer, or the percent weight loss of cut fruit over time to approximate the liquid leak as described in Example 4. It includes.

Applicants could also determine the hardness of the various fruits simply by tasting the fruits. Moreover, it was the applicant's first decision how the watermelons of the present invention had very hard pulp when compared to watermelons of the prior art. In the tasting test, Applicants also found that the Tri-X Brand 626 (Syngenta / Rogers-3 embryo), Extazy (Hazera-3 embryo) and Solitaire (Golden Valley-3 embryo) strains are hard pulp to very large. While it was found to have hard pulp, standard varieties of the prior art, such as the diploid royal star strain of Seminis, were found to have hard pulp.

Other important fruit features are quality, including the sweetness and the superiority of the fruit and skin color. Wener et al. (2001): Watermelon: Traits, Production and Marketing, Maynard, editor, ASHS Press, Alexandria VA. The most important of these properties is the bitter sugar, which is measured by bric and flavor. Flavor panel data illustrate a direct correlation between higher brix levels and superior flavor scores (Nip et al., (1968) Proc, Amer, Soc, Hort, Sci. 93: 547). Briggs levels increase as the fruit grows and ripens on the vines. Thus, immature fruits will have low sugar content that is unacceptable to consumers; If harvested too early, the edible tissue also cannot have a uniform color. A quantitative recommendation for watermelon was also published. Wener et al. Proposed a brix level between 10% and 14% brix, while the US Department of Agriculture described in detail in the "Definitions" section that the sweetness of at least 8 brixes is very good and the sweetness of at least 10 brixes is very good. Established standards. Despite some changes in the recommendation and standard values, fruit sugar is indisputably an important feature of watermelon.

Characteristics of the watermelon of the present invention

Fruit Hard

The pulp of the watermelon plant fruits of the present invention is harder and contains more liquid than the fruit pulp of the watermelon cultivars of the prior art. In the watermelon of the prior art, mature edible pulp from diploid genotypes is softer than both triploid and tetraploid genotypes. Regardless of the level of drainage, the variation in fruit firmness within the strain is not significant. In general, standard diploid varieties produce fruits ranging from soft pulp to hard pulp (ie, less than 1.0 lbf to about 1.5 lbf hard at maturity). Standard triplet lines typically produce hard or very hard fruit (ie between 1.5 lbf and less than about 3.0 lbf hard at maturity). Standard triplet hybrids produce seedless fruit with moderate pulp hardness ranging from about 1.3 lbf to 2.5 lbf at maturity. Table 1 shows the pulp hardening data from the prior art for commercial hybrids and inbred watermelon systems.

All rigid measurements here are made using a model FT011 penetrometer from QA Supplies in Norfolk, Virginia with a probe diameter of 8 mm. Readings are made and recorded in pound-force, a British engineering unit of measure for pressure abbreviated lbf, and converted to Newtons according to the following equation: 1 lbf = 4.448 Newtons. Fruits were cut horizontally in the middle between the flower and stem ends of each fruit. Applicants made 3-5 readings per fruit and took samples from the center of each cut fruit. The hard data reported is the average of these 3-5 readings.

TABLE 1

Investigate the rigidity of typical watermelon cultivars and crossbreeding lines. Average rigidity readings are expressed in pound force according to the method described herein.

system origin Drainage stiffness Tri-X 313 Syngenta / Rogers Triplicate 1.4 Millionaire Harris Moran Triplicate 1.8 Revolution SunSeeds Triplicate 1.7 Majestic Seminis Triplicate 1.7 Olympia Seminis Triplicate 1.6 Omega Seminis Triplicate 1.5 PS110-5288-9 Seminis Triplicate 2.3 4082 Seminis Triplicate 2.0 4084 Seminis Triplicate 1.5 4090 Seminis Triplicate 1.6 4133 Seminis Triplicate 2.2 4134 Seminis Triplicate 2.4 4135 Seminis Triplicate 2.2 4137 Seminis Triplicate 2.7 4138 Seminis Triplicate 2.2 47602A Seminis Diploid 1.5 4203 Seminis Diploid 1.4 Cooperstown Seminis Triplicate 1.5 Fenway Seminis Triplicate 2.1 Sentinel Seminis Diploid 1.4 W-1128 Seminis Diploid 1.4 W-1119 Seminis Diploid 1.6 BSI 2532 Seminis Diploid 1.7 BSI 2527 Seminis Diploid 1.3 W-2068 Seminis Diploid 1.1 W-2741 Seminis Diploid 1.3 W-1488 Seminis Diploid 1.7 BSI 2543 Seminis Diploid 1.2

Compared to the watermelon systems of the prior art, the fruits of the present invention have both very hard pulp and sugar content. Table 2 shows the flesh hardening and sugar content from watermelon strain PI296341, which was used as the source of the novel hard flesh fruit of the present invention, hybrid strains were produced according to the methods described herein. Sugar measurements were determined quantitatively using a refractometer (Leica Microsystems Model AR200, Reichert Inc., Depew, NY) according to the manufacturer's instructions. One measurement was taken from half of the fruit cut horizontally. Data was recorded as average.

Comparing the hard readings of Table 2 with the values of Table 1, the flesh of the watermelon of the present invention is considerably harder than the watermelon flesh of the prior art. In particular, the watermelon of the present invention resists a pressure of at least about 3.0 lbf, preferably at least about 3.5 lbf, more preferably at least about 4 lbf and most preferably at least about 5 lbf.

Moreover, as can be seen from Table 2, the watermelon of the present invention has a sweet taste. In particular, the watermelon exhibits a sugar content of at least about 6 brix, more preferably at least about 8 brix and most preferably at least about 10 brix.

TABLE 2

Hardness and sugar content of the hybrid system improved from the sub-system and from the present invention and PI296341 sources described herein. Hard readings are in pound force and the sugar content is expressed as% brix. Both measurements are described herein.

line origin Drainage stiffness Sugar content PI296341 USDA Collection Diploid 13.5 1.6 7132 The present invention Triplicate 4.7 10.2 7133 The present invention Triplicate 6.2 11.7 4201 The present invention Diploid 8.0 9.7 4203 The present invention Diploid 7.8 10.8 4204 The present invention Diploid 6.5 9.7 4207 The present invention Diploid 6.5 10

Liquid retention

In addition, the fruits of the present invention retain more liquid than the fruits of the prior art. Example 4 describes a study illustrating this liquid retention property. This study compares the liquid leak rate of the cut fruit from the watermelon of the present invention with the liquid leak rate of the cut fruit from the watermelon of the prior art when stored at 4 ° C. The results of this study are illustrated in Table 2. This study measures the percentage weight loss of cut fruit over time. This measurement is close to liquid loss, so 95-98% of the weight loss is due to liquid leakage. The remaining weight loss is due to the leakage of soluble solids and other components of the fruit, such as acids. The main conclusion from these data is that the processed watermelon of the present invention loses less liquid over time than the processed fruits of standard known cultivars.

The watermelon of the present invention loses less than about 4% by weight after 3 days storage at 4 ° C. Preferably, the fruit of the invention loses less than about 3.5% by weight after 3 days storage at 4 ° C., more preferably less than about 3% by weight, even more preferably less than about 2% by weight, most preferably Less than 1.5% by weight.

In addition, the watermelon of the present invention loses less than about 5% by weight after one week of storage at 4 ° C. Preferably, the fruits of the present invention lose less than about 4% by weight, more preferably less than about 3% by weight, even more preferably less than about 2.5% by weight after a week of storage at 4 ° C.

In addition to having a pulp holding a liquid, the fruit of the present invention is sweet. In particular, these watermelons have a sweetness of at least about 6 brix, more preferably at least about 8 brix, most preferably at least about 10 brix.

Other characteristics

Watermelon plants of the present invention may or may not have seeds. Methods for obtaining diploid, triploid and tetraploid plants are well known in the art. In particular, diploid and triploid watermelon plants and methods for obtaining seeds of the invention are described in detail below. Tetraploid plants of the present invention can be readily obtained by one of ordinary skill in the art using known cell biology techniques and the diploid plants described below.

Using standard breeding techniques, those skilled in the art can obtain the watermelon of the present invention with desirable properties in addition to those described above, while retaining extremely hard flesh and liquid retaining flesh properties. For example, breeders can easily obtain a watermelon of the present invention having a particular size, or a particular flesh color or peel pattern.

Breeding techniques Inbreeding  And hybrid strains

The watermelon strains of the present invention began in 2000 and were developed in the United States (Georgia, Florida and California), Mexico and Guatemala. Furthermore, watermelon strains began in 2003 and grew in Florida, Georgia, and California to assess outdoor performance and compliance. In addition, diploid and triploid watermelon hybrids made from strains that produce watermelon with extremely hard pulp and / or liquid retaining pulp at maturity were assessed outdoors in 2003 and 2004 in Florida, California, and Mexico. It became. Specific hybridization and the assessment of the rigidity and quality of the resulting fruits are described in detail in the "Examples" section.

For most breeding purposes, commercial breeders work with germplasm, often referred to as the "cultivated type." This germplasm is easy to breed because it is generally easier to perform in the assessment of horticultural studies. The performance benefits offered by the cults offset each other with the lack of allelic diversity. This is an exchange that allows breeders to perform with culturing embryos with better performance, but with a lack of allelic diversity. Breeders generally allow this exchange because progress is faster when working with cultivated materials than when breeding from genetically diverse sources.

In contrast, back exchange occurs when the breeder takes either broad intracross or cross breeding. In these examples, breeders typically cross cultivated embryonic and non-cultivated. In this breeding, the breeder can gain access to new alleles from the non-cultivated type, but must overcome the genetic drag associated with the donor parent. Because of the difficulty of this breeding strategy, this approach often fails with fertility or fertility problems. The difficulty of this breeding strategy applies to numerous crops and is illustrated by the important disease-resistant phenotypes first described in tomato in 1944 (Smith, Proc. Am. Soc. Hort. Sci. 44: 413–416). In this cross, nematode disease resistance was transferred into tomatoes grown from L. peruvianum (PI128657). Despite spurred research on breeding, it was difficult until the mid-1970s that breeders produced successful strains that overcome genetic attraction and convey these characteristics. Moreover, even today, tomato breeders pass the disease resistance gene from only one of their parents to a hybrid. This allows the remaining genetic attraction to be blocked. Continuing invention in such breeding methods has been recognized by USPTO (US Pat. Nos. 6,414,226, 6,096,994, 5,866,764 and 6,639,132).

In watermelons, plant-derived (PI) deposit lines are typically lines that produce hard fruits with small white flesh and a very poor taste (even bitter). Although these strains have such poor horticultural quality, some watermelon breeders have tried breeding with these PI strains because, like some other crop breeders, the PI strains are likely to contain new alleles. Today, the most commonly attempted breeding purpose for the use of PI lineage series is to introduce new disease resistance genes. The introduction of new resistance genes from the PI strain into acceptable commercial forms is a long and sometimes difficult process. This method can be difficult because the properties can be polygenic, have low heritability, linkage drag, or a combination of these three.

The breeding project began with extensive crosses between cultivated watermelons and PI number 296341 from the USDA collection (Regional Plant Introduction Station in Griffin, Georgia). It was founded in 1964 by U.S. Since it has been deposited in the Plant Introduction System, it is available to watermelon breeders.

However, the original intention of the project was not to make watermelons with hard pulp and / or liquid retaining pulp. Rather, the original intent of the project is the Fusarium , referred to here as FON race 2. wilt , especially Fusarium oxysporum f. sp . It was intended to introduce tolerance into niveum race 2. Although some commercial watermelons contain resistance to FON race 2, the possibility of using PI296341 as a source of resistance has been known for many years (Netzer (1989) Plant Disease 73: 518; Martyn and Netzer (1991) Hortscience 26: 429–. 432; Wehner et al. ((2001): Watermelon: characteristics, production and marketing.Maynard, editor.ASHS Press.Alexia, VA). The absence of watermelons in the commercial line suggests the introduction of properties from a wide range of crosses, making it difficult to produce commercially successful crosses and hybrids.

In addition to being resistant to FON race2, the PI296341 is characterized by having very small round fruits weighing between 4 and 6 inches in diameter and weighing between 1 and 2.6 pounds. Fruit pulp is white, very hard, and has a low soluble solids content (Table 2). Sensory evaluation of these fruits ranges from no recognition of sweetness to bitter taste. As described in the "Examples" section below, the cross-bred watermelon plants of the present invention have other desirable qualities, including watermelons and sugars, with extremely hard pulp properties and / or liquid retention pulp properties (extremely hard parents). Can be obtained by crossing watermelons (recurring parents) that do not have extremely hard flesh with characteristics. An extremely hard parent may be the Plant Introduction Collection Accession No. 296341.

Those skilled in the art will perform various repetitive hybridizations, select (i) extremely hard flesh and / or liquid retaining pulp properties and (ii) sugar properties, and finally create a cross-bred watermelon strain with these characteristics. By self-pollinating selected plants of, it may be possible to introduce extremely hard pulp and / or liquid retention properties into the repeat parent. One possible way to make this introduction is described in the "Examples" section below.

Applicants made crossbreeding line 3347, which produces the sweet and extremely hard fruit according to the present invention using the method described above and also in the "Examples" section. In particular, reference may be made to Example 5. Inbreeding line 3347 was deposited with NCIMB and received accession number NCIMB 41230. Details of the deposit follow the "Examples" section.

Using known methods, breeders can obtain a diploid, triploid, and tetraploid inbred lineage of watermelon with (i) a fleshy property that retains extremely hard flesh and / or liquid and (ii) a sugar content. .

In addition, since the extremely hard flesh and liquid retention properties of the present invention are dominantly inherited, breeders can obtain hybrids using the watermelons of the present invention. Hybrids can be either diploid or triploid. In particular, breeders are capable of producing diploid and triploid watermelon plants with fruits having extremely hard flesh and / or liquid retaining fleshy and sugary properties, respectively, and cross-bred watermelons with the desired fleshy and sugary properties described above. The plants were crossed to cultivars that did not have extremely hard flesh of diploids or tetraploids. In addition, the extremely hard pulp parent used to make the hybrid may be used to obtain a sweet, extremely hard pulp and / or liquid retaining pulp watermelon with other desirable properties such as special size and / or color. have.

One skilled in the art recognizes that there are several breeding methods, including gravimetric screening, lineage screening, repeat screening and hybridization, which are used to introduce new properties into commercial germplasm. By way of example and not by way of limitation, the introduction of watermelon properties with extremely brittle flesh at maturity with high brix levels is described below.

Example  1: formation of F1 strains Expulsion

In the summer of 2000, four first offspring (F1) generation lines were obtained by crossing the PI296341 with four seminised crossbreeding lines as an amcrew. The four diploid cross-breeding lines used were W-2388, W-1128, W-1119 and W-1488. The strain W-2388 has been extended with a length-to-width (L / W) ratio of 1.8 to 2.2: 1. The shell color and pattern is a medium green background with a wider darker stripe. The phenotype of this shape and the peel pattern is known to those skilled in the art as an "extended dark blotched stripe" watermelon. The fruit of strain W-1128 is a round ellipse with a L / W ratio of 1.0 to 1.2: 1, with a light green to medium green background and narrower, darker green stripes. This phenotype is known to those skilled in the art as round oval watermelon fruits with "narrow (or tiger) stripes". Fruits of strain W-1119 are oval to very round with a L / W ratio of 1.1 to 1.3: 1. The shell color is a medium green background with a wider, darker green stripe. This phenotype is known to those skilled in the art as a "round oval dark stained stripe" watermelon. Fruits of strain W-1488 are round in shape with an L / W ratio of 1.0-1.1: 1. The bark color is a pale green with a slightly pale stain / net pattern background. This phenotype is known to those skilled in the art as "round gray (or light green) watermelon." These four lines provide an array of phenotypic diversity among the cultivated types.

In the fall of 2000, each F1 was used as a crew to explode with the four crossbreeds above, resulting in generation 1 of BC1.

Plants of BC1 generation grew in the spring of 2001, and selection was based on overall sound growth. Since many BC1 and even BC2 plants died, it was difficult to introduce alleles from the PI strain into cultivars. Changes in vine vigor were observed in relation to viability. Vine growth was thought to be associated with overall growth and possibly pathogen resistance.

Each BC1 lineage derived from the original four inbred individuals was crossbred with Amcrue as follows:

1. [[W-1128 × PI296341] F1 × W-1128] (this is W-1128 BC1) × W-1128

2. [[W-1119 × PI296341] F1 × W-1119] (this is W-1119 BC1) × W-1119

3. [[W-1488 × PI296341] F1 × W-1488] (This is W-1488 BC1) × W-1488

4. [[W-2388 × PI296341] F1 × W-2388] (this is W-2388 BC1) × W-2068

5. [[W-2388 × PI296341] F1 × W-2388] (this is W-2388 BC1) × BSI-2543

6. [[W-2388 × PI296341] F1 × W-2388] (This is W-2388 BC1) × BSI-2527

In these six crosses, the first three are repeat parental hybridization. Mating number 4 was strain W-2068, very similar to the original parent W-2388. Crosses 5 and 6 were new inbred individuals. The repetitive termination hybridization program is for adding one or more new properties from the donor parent (in this case PI296431), while retaining the phenotype of the repeat parent. However, since watermelon breeding is a dynamic process, it is common to change repetitive parents because newer crossbreeding lines progress simultaneously. Thus, mating 4-6 did not technically make BC2 generation. For clarity of generations, these crosses will be referred to as BC2 ^* generations.

BC2 and BC2 ^* generations were grown in the summer of 2001. As in the BC1 generation, screening for vine growth was performed. These selected crews were used to create BC3 and BC3 ^* generations.

1.W-1128 BC2 × W-1128 = BC3

2.W-1119 BC2 × W-2741 = BC3 ^*

3.W-1488 BC2 × W-1488 = BC3

4.W-2068 BC2 ^* × W-2068 = BC3 ^*

5.BSI-2543 BC2 ^* × BSI-2543 = BC3 ^*

6.BSI-2527 BC2 ^* × BSI-2527 = BC3 ^*

In the fall of 2001, BC3 and BC3 ^* strains grew, and vine growth was applied to the selection criteria. Thereafter, selected plants were crossed and mated to produce BC4 and BC4 ^* generations, respectively.

7.W-1128 BC3 × W-1128 = BC4

8.W-2741 BC3 ^* × W-2741 = BC4 ^*

9.W-1488 BC3 × W-1488 = BC4

10.W-2068 BC3 ^* × W-2068 = BC4 ^*

11.BSI-2543 BC3 ^* × BSI-2543 = BC4 ^*

12.BSI-2527 BC3 ^* × BSI-2527 = BC4 ^*

In addition to sorting by vine growth, test results of BC3 and BC3 ^* fruits, including BC4 and BC4 ^* generation seeds, have yielded unexpected findings. When assessed by the current horticultural character, the quality characteristics of the fruits were tested, even though the BC3 generation is still incomplete. Although most fruits have incomplete quality, the breeder's observations for small quantities of fruit include the following: "excellent fruit color, sweetness and extremely hard flesh-like apples". An unexpected finding is that extremely hard flesh and sweet flesh can be made. The possibility of making sweet fruit flesh combined with extremely hard fruit flesh for cut fruit slices on the market results in a branching point for breeding purposes. Applicants have initiated a new project with the goal of making extremely hard flesh watermelon with a sweet taste.

Example  2: Data on the self-pollination and initial pulp firmness of plants yielding extremely hard pulp fruits

In the spring of 2002, the BC4 / BC4 ^* generation grew and qualitatively assessed for sugar content, fruit flesh hardening and horticultural characteristics. Based on these criteria, plants were selected to obtain the next generation. However, instead of obtaining another outgrowth generation, each selected one was self pollinated from improved lines simultaneously. The crossover gave BC4S1 / BC4 ^* S1 generations.

In the summer of 2002, the BC4S1 / BC4 ^* S1 generation grew and qualitatively assessed for sweetness, fruit flesh hardening and horticultural characteristics. Based on these criteria, plants were selected to obtain the next generation. Self-pollination of selected plants yielded BC4S2 / BC4 ^* S2 generations.

In the fall of 2002, two generations of BC4S2 / BC4S ^* were grown and qualitatively evaluated for their sweetness, fruit flesh hardening and horticultural characteristics. Based on these criteria, plants were selected to obtain the next generation. Self-pollination of selected plants yielded BC4S3 / BC4S ^* 3 generations.

In the spring of 2003, three generations of BC4S3 / BC4S ^* were grown and qualitatively evaluated for their sweetness, fruit flesh hardening and horticultural characteristics. Based on these criteria, plants were selected to obtain the next generation. Self-pollination of selected plants yielded BC4S4 / BC4S ^* 4 generations.

For BC4S3 fruits, both qualitative and quantitative data were obtained for hardening the pulp. In particular, 93 fruits from individual BC4S3 plants were evaluated for hardening as permeability (model FT011 with 8 mm diameter probe, QA Supplies, Norfolk, VA). The FT011 penetrometer has a gauge that reads PF, an irregular error for pound force. Pound force is the British engineering measurement scale for pressure, and is abbreviated abbreviated appropriately. The conversion from the UK's measurement system to the International Unit System (SI) is 1 lbf = 4.448 Newtons. For all flesh hardening measurements using a penetrometer, mature fruits were removed from the plants and cut in the horizontal direction. For orientation, the fruits have a stem end and a flower end. Cutting in the horizontal direction means that the fruit is split in half so that each half has a flower or stem end at the furthest distance from the cut. Samples were taken from the center of the cut fruit. For diploid fruits, sampling was performed in a seeded ring. Although triploid fruits had little seed, sampling was done in the same core area of the split fruit. Each half was applied to a perimeter and three to five readings per fruit were taken. Hard data was recorded as the mean value of 3-5 readings.

Figure 1 shows that even after several generations of attempts to fix a firm pulp phenotype with acceptable horticultural features, including sugar content, significant fruit pulp rigidity changes are still present in these samples. Although the data in FIG. 1 exhibits an important variety, it is evident that there is an improvement in fruit firmness. Arrows show the average hardness rating of repeat parents. Even in this early generation of product development, about 43% of fruits have firmness measurements of 4 lbf or more.

Several phenotypes are determined by the genotype of one locus. Their simple properties, similar to those studied by Mendel, appear in discrete categories such as green or yellow seeds. However, most of the changes observed in nature are continuous, as can be seen in wild corn or human blood pressure. 1 shows a pattern of continuous types of hard pulp changes similar to the normal distribution. Unlike simply inherited properties, continuous changes can be the result of multigene inheritance. Loci that affect continuous changes are referred to as quantitative characteristic loci or QTLs. Changes in the phenotype of quantitative properties are the result of allele composition and environmental impact in QTLs. Applicants have identified several possible causes for the change: (1) fruit hardening properties are adjustable by several to many QTLs; (2) fruit hardening properties can be caused by one or a few genes, but have low heritability; (3) The property can be both polygenic and low heritability. Those skilled in the art recognize that the market requires product uniformity. Thus, the utility of the present invention is higher for properties with high heritability that are not significantly affected by the environment. The heritability of a trait is the proportion of phenotypic diversity that contributes to genetic diversity. This ratio varies between 0 and 1. Thus, a property with a heritability of nearly 1.0 is not greatly affected by the environment. Since the fruit hard change described in FIG. 1 does not explain the cause of the variety, further experiments were conducted to determine the cause of the variety as described in the examples below.

Example  3: extremely hard pulp Diploid  Generations of hybrids

In the fall of 2002, in addition to self pollination, selected BC4S2 / BC4S ^* 2 generation plants were bred with other commercial crossbreeds that did not contain an extremely hard flesh phenotype. These crosses were designed to test to what extent predominantly hard flesh properties could be inherited in hybrid combinations. Those skilled in the art will recognize the importance of establishing how evolved properties in inbred lines function well in hybrid combinations.

In the spring of 2003, these test hybrids were evaluated in Florida and California. Although many hybrid combinations have been tested with these trials, most of these data have not been presented. Instead, data from four outstanding hybrids from trials in both regions are shown in Tables 3 and 4. Hybrids were evaluated by a number of criteria including shell color patterns. For these hybrids, all have blobed striped patterns, named MS. In addition, fruit length and width, peel thickness, pulp, color, firmness and sugar level were evaluated.

In determining the sugar level quantitatively, Applicants used a refractometer to measure brix levels. In particular, Briggs levels were measured according to the manufacturer's instructions with a hand operated digital refractometer (Leica Microsystems Model AR200, Reichert Inc., Depew, NY). Briggs levels were determined after a firm squeeze of the sample fruit until the droplets dropped into the wells of the refractometer, followed by a hard reading by the penetrometer. One Briggs measurement was taken from half of the cut fruit and the data were reported as the mean.

Tables 3 and 4 show that the test hybrids show small changes between the test sites. However, the data taken together show that this superior hybrid combination progressed evenly in both regions. In particular, these hybrids constantly have very hard pulp as measured by the unit pound force of pressure, and have very good soluble solids, as specified by Brix%.

The fruit pulp hardening data obtained from the two regions provide an explanation of the genetics of that property and answers the question of heritability presented by the data presented in FIG. 1. First, these data show that very hard pulp properties can be transferred from a single parent to the F1 hybrid. In other words, the loci selected in the manner described here are dominant because they are fruity. This is important for designing breeding strategies. Moreover, the persistence of hard measurements across several hybrids in both regions shows that the extremely hard flesh alleles selected by the method described here have a high degree of genetic potential. Those skilled in the art will recognize the importance of constructing commercial lines with highly heritable horticultural properties. In particular, these varieties enable growers to produce crops with uniform market specifications.

TABLE 3

TABLE 4

Example  4: Evaluation of Liquid Retention Pulp Characteristics of Extremely Hard Pulp Hybrids

As described herein, studies agree that products processed in minimal quantities have a short shelf life of up to 2-3 days (Perkins-Veazie et al. (1998) Hortscience 33: 605; Wehner et al .: Watermelon: features, production and marketing, Maynard, editor.ASHS Press, Alexandria, VA, 2001). Although the maximum shelf life of the cut watermelon is only a few days, the quality of the product begins to degrade quickly after being processed. In cut products provided in plastic food containers, consumers see this rapid deterioration because liquid leaks out of the cut product and accumulates at the bottom of the container.

Mature fruits from the California hybrid test of 2003 (Example 3, Table 4) were evaluated for leaks using the liquid retention test described herein (see FIG. 2). This test was conducted at 4 ° C. Fruits from the test hybrids 4201, 4204 and 4207 were tested with standard diploid and triploid controls. The test hybrids had a hard reading of 8.0 lbf, 7.0 lbf and 6.0 lbf, respectively, and exhibited extremely hard flesh properties (Table 4). Controls showed firm readings of <2.0 lbf and <2.5 lbf, respectively. To measure the liquid loss, the edible portions of the fruits were cut to about 1 inch cube size and weighed. The reason for choosing an approximately 1 inch cube is that it best fits the size of the processed product found at the retail outlet. After the 16 day period had elapsed, the samples were weighed again and the weight loss was calculated to estimate the liquid loss.

Figure 2 graphically shows the weight loss percentage of these samples after 16 days. A number of samples in the system were tested, with triangles, circles and squares representing the mean at each time point and the standard deviation of the samples shown as bars. The data in FIG. 2 shows that the difference in weight loss is large between the controls with softer fruit pulp and those with extremely hard pulp properties. The difference between the control and test hybrids with an extremely hard flesh phenotype is evident at the first time point, about 6.5 hours after the sample is cut. Thus, cut products from standard cultivars may have a shelf life of up to 2-3 days, but the degradation of the product begins almost immediately after cutting. These data show that the extremely hard flesh lines developed using the method described herein can resist rapid liquid leakage that is common in sliced watermelon fruits. Because these extremely hard flesh fruits can retain liquid after cutting, these watermelons will last longer in the market for watermelons processed in minimal quantities.

Example  5: final self pollination and Triplicate  Hybrids Operation  And evaluation

In the summer of 2003, the BC4S4 / BC4S ^* 4 generations described in Example 2 were grown and qualitatively evaluated for sugar content, fruit flesh hardening and horticultural characteristics. Based on these criteria, plants were selected for the next generation of crops. Self-pollination gave BC4S5 / BC4S ^* 5 generations.

In the fall of 2003, five generations of BC4S5 / BC4S ^* were grown and qualitatively evaluated for their sweetness, fruit crumb hardness and horticultural characteristics. Based on these criteria, plants were selected to produce the next generation. Self-pollination gave BC4S6 / BC4S ^* 6 generations.

In addition, quantitative hard data was collected from BC4S5, a qualitatively sweet strain. In particular, 26 systems were tested and the results are shown in Table 5 below. Fourteen of these lines were single fruit tests, and the remaining 12 lines had two or three fruits tested per line. Hardness among the 26 systems ranged from as low as 4.0 lbf to as high as 8.0 lbf. For lines with multiple samples, 11 of the 12 lines showed no difference in permeability measurements. Only one strain showed a 1 lbf difference in permeometer measurements. These data provide an explanation for the question by FIG. 1 that showed diversity in extremely hard pulp properties in the BC4S3 generation. In particular, it is unclear whether the extremely hard pulp properties in the BC4S3 generation show low or high heritability. Numerous strains developed at the same time have been improved, but different fruit hardening readings suggest that extremely hard pulp is multigene in nature. The changes in the very low strains shown in Table 5, along with the test hybrid data shown in Tables 3 and 4, show that the extremely hard flesh features have high heritability. Those skilled in the art will recognize the importance of creating commercial lines with highly heritable horticultural properties, as these cultivars enable growers to produce crops with uniform market specifications.

TABLE 5

In-situ evaluation from BC4S5 / BC4S ^* 5 generation

In addition to the self-pollination described above, selected BC4S4 / BC4S ^* generation 4 plants were crossed with other commercial tetraploid myoblasts that did not contain an extremely hard phenotype. These tetraploid x diploid crosses were made to test the extent to which the extremely hard pulp character can be dominantly inherited in a triplet hybrid combination. As can be seen in Table 6 below, the extremely hard pulp properties were inherited by triploid seedless fruit.

TABLE 6

Mature fruit pulp hard and sweetness. Rigidity was measured as described herein with a penetrometer.

All references cited herein are incorporated herein in their entirety.

Deposit Information

The hybridization and hybrid watermelon strains 3347 owned by Seminis Vegetable Seeds disclosed above and described in the appended claims are described in NCIMB Ltd, 23 St. It was deposited at Machar Drive, Aberdeen AB24 3RY. The date of deposit was 1 July 2004. The deposit of 2,500 seeds for this variant was taken from the same deposit maintained by Seminis Vegetable Seeds before the filing date of this application. At the time of registration of the patent, all restrictions on the deposit can be removed, and the deposit is 37 C.F.R. All of the requirements of Sec. 1.801 through 1.809 may be met. NCIMB Accession No. for Inbred Line 3347 was deposited as NCIMB 41230.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of understanding and clarity, since the scope of the invention is limited only by the appended claims, any changes and modifications are within the scope of the invention. It will be apparent that it may be practiced.

Claims (49)

Watermelon plants that produce fruits that have extremely hard pulp and soluble solids of at least about 6 brics. The watermelon plant of claim 1 wherein said extremely hard flesh is resistant to a pressure of at least about 3.5 lbf. The watermelon plant of claim 2 wherein said extremely hard flesh is resistant to a pressure of at least about 4.0 lbf. The watermelon plant of claim 3 wherein said extremely hard flesh is resistant to a pressure of at least about 5.0 lbf. The method of claim 4. The extremely hard flesh is watermelon resistant to a pressure of at least about 6.0 lbf. 6. The watermelon plant of claim 5 wherein the extremely hard flesh is resistant to a pressure of at least about 8.0 lbf. The fruit of claim 1 having good soluble solids. 8. Fruit according to claim 7, having very good soluble solids. The watermelon plant of claim 1 wherein said plant produces at least about 1.5 kg of fruit. 10. The watermelon plant of claim 9 wherein said plant produces at least about 3.0 kg of fruit. The watermelon plant of claim 10 wherein said plant produces at least about 4.5 kg of fruit. 12. The watermelon plant of claim 11 wherein said plant produces at least about 6.0 kg of fruit. The watermelon plant of claim 1, wherein the plant produces a fruit having red pulp. The watermelon plant of claim 1 wherein said plant produces a fruit with a yellow pulp. The watermelon plant of claim 1, wherein the plant produces an orange fleshed fruit. The watermelon plant according to claim 1, wherein said plant is a diploid. The watermelon plant according to claim 1, wherein the plant is a tetraploid. The watermelon plant of claim 1, wherein said plant is a triploid. A watermelon plant according to claim 1 which has extremely hard fleshy properties and soluble solids of the plant produced from seeds deposited under accession number NCIMB 41230. Seed from the plant of claim 19. Pollen from the plant of claim 19. Egg cells from the plant of claim 19. Nutritional tissue derived from the plant of claim 19. Watermelon plant regenerated from the tissue of claim 23. A method of producing hybrid watermelon seeds, comprising crossing a cross-breeding watermelon plant of claim 1 with a second watermelon plant and harvesting the resulting hybrid watermelon seed. A hybrid watermelon plant produced by growing a hybrid watermelon seed as a result of claim 25. A method of producing the watermelon plant of claim 1 comprising the following steps: (1) mating watermelon species with good soluble solids with watermelons with extremely hard flesh; (2) subjecting the watermelon species with good soluble solids to at least one time of hybridization; And (3) self-polishing one or more times the composted products of step (2) having extremely hard flesh and at least 6 brix soluble solids. The method of claim 27, wherein the extremely hard fleshy watermelon species is USDA collection number PI296341. Watermelon harvested from the plant according to claim 1. Watermelon pulp derived from the watermelon of claim 29. A number of watermelon plants according to claim 1 grown in the field. A watermelon plant that produces a fruit having a liquid retaining pulp and a soluble solids of at least about 6 brics. 33. The watermelon plant of claim 32 wherein the liquid retaining pulp loses about 3.5% by weight after three days storage at 4 ° C upon cutting. 34. The watermelon plant of claim 33 wherein the liquid retaining pulp loses about 3% by weight after three days storage at 4 ° C upon cutting. 35. The watermelon plant of claim 34 wherein the liquid retaining pulp loses about 2% by weight after 3 days storage at 4 ° C upon cutting. 36. The watermelon plant of claim 35 wherein the liquid retaining pulp loses about 1.5% by weight after three days storage at 4 ° C upon cutting. 33. The watermelon plant of claim 32 wherein the liquid retaining pulp loses about 5% by weight after one week storage at 4 ° C upon cutting. 38. The watermelon plant of claim 37 wherein the liquid retaining pulp loses about 4% by weight after one week storage at 4 ° C. The watermelon plant of claim 38 wherein said liquid retaining pulp loses about 3% by weight after one week storage at 4 ° C. upon cutting. 40. The watermelon plant of claim 39 wherein the liquid retaining pulp loses about 2.5% by weight after one week storage at 4 ° C upon cutting. 33. The fruit of claim 32, further having an extremely hard flesh. 42. The fruit of claim 41, wherein the extremely hard flesh is resistant to a pressure of at least about 3.5 lbf. 43. The fruit of claim 42, wherein the extremely hard flesh is resistant to a pressure of at least about 4.0 lbf. 44. The watermelon plant of claim 43 wherein the extremely hard flesh is resistant to a pressure of at least about 5.0 lbf. 45. The watermelon plant of claim 44 wherein said extremely hard flesh is resistant to a pressure of at least about 6.0 lbf. 46. The watermelon plant of claim 45 wherein the extremely hard flesh is resistant to a pressure of at least about 8.0 lbf. 33. The watermelon plant of claim 32 having a soluble solids of at least about 8 brics. 48. The watermelon plant of claim 47 having a soluble solids of at least about 10 brics. The watermelon plant of claim 48 having a soluble solids of at least about 11.5 brics.

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