JP6161020B2 - Method for accelerating zinc accumulation in foliage and grain part of plant body and crop produced by the method - Google Patents

Description

      The present invention relates to a cultivation method for accumulating zinc at a high concentration in a plant, and more specifically, a cultivation method for accumulating zinc at a high concentration in a stem / leaf part and a grain part (edible part) of an agricultural product. And crops produced using the method.

Zinc is an essential heavy metal element indispensable for human beings. However, recent changes in the dietary habits of humans, including Japanese, have led to a decrease in zinc intake from food, resulting in various problems such as abnormal taste and decreased reproductive function. . Inferred from food supply and demand data, it is shown that approximately 50% of the world's population is at risk of zinc deficiency.

In order to simply compensate for the shortage of zinc intake, it is sufficient to ingest foods rich in zinc, such as oysters, but this causes a bias in nutrition. Therefore, as a method of eliminating zinc shortage while considering other nutritional aspects, intake of zinc from vegetables rich in minerals can be considered. However, in order to satisfy the required amount of zinc obtained from vegetables, it is necessary to consume a considerable amount of vegetables. By the way, vegetarians fall into a category with a high risk of zinc deficiency among humans.

Therefore, as a means for solving such a problem, it is conceivable to secure a sufficient zinc intake by increasing the amount of zinc accumulated in the edible portion of the crop. If this technology is put to practical use, it will be possible to secure the necessary amount of zinc with realistic vegetable intake, and it can be expected to lead to the solution of the problem of insufficient zinc intake.

Currently, as a method of increasing the amount of zinc accumulated in plants, a long-lasting zinc agent is introduced into the soil (Patent Document 1) and a soil improver containing various mineral agents is used (Patent Document 2). ). However, with these methods, new materials are thrown into the soil. Therefore, when considering the stabilization of the quality of crops, the method of adding a large amount of material to the cultivated soil always affects the effect of the input material on food production (eg material cost, product quality, etc.). There is a need to monitor.

In addition, there is an attempt to give added value to plants by giving a foliar spray containing substances and nutrient elements that promote plant metabolism (Patent Document 3), but it promotes absorption of specific substances in the roots It is not a thing.

In plant physiology research conducted so far, the mechanism of zinc accumulation in plants has been clarified by experiments using plants with high zinc accumulation (Non-patent Document 1).

Among them, experiments with cruciferous plants have revealed the dynamics of zinc in the roots. In an experiment using Arabidopsis, a gene of a zinc transporter protein involved in root zinc dynamics has also been identified (Non-patent Document 2).

In these studies, application to removal of zinc from soil with a high concentration of zinc has been studied, and there are few examples of studying to increase the zinc content in edible vegetables. If a technology that applies such a mechanism is put into practical use to create a crop with high zinc accumulation, it is necessary to control the expression of the gene. In such cases, gene recombination techniques are used. In the case of technologies using genetic recombination, it is expected that there will be many barriers that must be exceeded for these technologies to be accepted from the market.

JP 2000-327464 long-lasting zinc agent JP 2006-306683 Mineral agent for plant growth and soil improver containing the same JP 2006-265199 Foliar spray and production method thereof

Papoyan et al., (2007) New Phytologist 175: 51-58 Kraemer (2010) Annu. Rev. Plant Biol. 61: 517-534 Sanita´ di Toppiand Gabbrielli (1999) Environ. Exp. Bot. 41: 105-130 Food Composition Table 2010 (Ministry of Education, Culture, Sports, Science and Technology)

As mentioned above, the introduction of new materials into the soil affects the growth of plants, and even if genetic modification technology is used by applying previous research knowledge, that technology is still in today's society. However, the conventional technology has various problems such as being not easily accepted. Also, in the conventional method, few attempts have been made to promote the absorption of specific substances in the roots by applying a foliar spray to plants.

The object of the present invention is to solve the problems of the prior art, and it is easy to accumulate zinc in the leaves, stems and grain parts (edible parts) of plants, especially crops. It is to provide a way to promote the increase.

A thiol group (sulfhydryl group) is a substituent having hydrogenated sulfur represented by the chemical formula -SH. It is a highly reactive substituent and has the property of being easily oxidized to a more chemically stable disulfide (—S—S—). Examples of the low molecular weight compound having a thiol group include glutathione, cysteine, and coenzyme A. Among them, it has been confirmed that glutathione has an influence on the dynamics of heavy metal elements in plant cells from previous studies (Non-patent Document 3). Therefore, in the present invention, the amount of zinc absorbed by the plant from the root and the zinc absorbed by the plant by giving glutathione to the leaves of the plant and changing the rhizosphere situation and the physiological state of the root. Increase the amount of plant body transferred to the above-ground part.

Specifically, MES-NaOH (pH = 6.1) with pH buffering capacity to maintain the pH of the solution at the same level as that of plant apoplasts , and a surfactant to penetrate the components of the solution into the leaves Applying glutathione solution consisting of a certain Triton X-100 and glutathione (reduced form) to the leaf surface in an appropriate amount, using appropriate means such as a brush, or applying it to the leaf surface enables application of glutathione limited to leaves. To do. Needless to say, the composition component, the appropriate amount, the appropriate number of times, and the means can be arbitrarily selected.

The operational effects of the above problem solving means are as follows. In other words, it is possible to easily increase the amount of zinc accumulated in the stems, leaves, and seeds of plants by applying or spraying a substance having a thiol group in the molecule such as glutathione from the leaf surface. Thus, it becomes possible to provide high value-added crops containing zinc at a high concentration to the market.

The amount of zinc accumulated in the stems and leaves of the plant is increased by administering glutathione, which is a substance having a thiol group, only to the leaves of the plant.
Details will be described below.

Use rape (variety: Norin 16) as the target plant. Cruciferous plants have a relatively strong resistance to heavy metal accumulation and are generally used as experimental materials for elucidating the heavy metal dynamics in plants. Moreover, in this experiment, the cultivation experiment by hydroponics was conducted as an ideal system for absorption of nutrient elements in the roots of plants. A modified hogland solution was used for hydroponics. Table 1 shows the composition. In general, Hoglund liquid is used for hydroponics experiments of field crops.

The apparatus and growth conditions used for hydroponics are as follows. That is, for the cultivation, an artificial meteor that can completely control the growth environment was used. Simulates 16-hour daytime in the device, and simulates 8-hour nighttime under light conditions at room temperature of 24 ° C and light conditions of about 270μmol · m ^-2 · s ^-1 (irradiated with fluorescent lamps from 5 directions) Then, at dark conditions, the environment was set to room temperature 16 ° C. and light conditions 0 μmol · m ⁻² · s ⁻¹ .

Since oilseed rape is a crop grown in the field, air was always supplied to the hydroponic liquid using an air pump during the hydroponic cultivation period in order to supply a sufficient amount of air to the roots. In this hydroponics, four plants were grown in each container using 1.5L containers. The hydroponic solution was changed twice a week during cultivation. The treatment experiment was performed for 2 weeks using the plant hydroponically cultivated by the above method for about 2 weeks after sowing. In this treatment experiment, there were many similarities in the dynamics of elements in the plant body, so CdCl ₂ was added to the hydroponic solution at a concentration of 10 μM for the purpose of observing the dynamics. In the treatment section using glutathione solution (referred to as glutathione treatment section), 250 μL per sheet is applied to the surface of the three leaves most developed with the glutathione solution shown in Table 2, twice a day in the morning and evening. Applied. Note that a compound containing zinc is not added to the glutathione solution.

After harvesting plants with glutathione treatment, measure the zinc content by dividing the plant body into shoots, ie, stems and leaves, and roots, ie, roots. did.

The sample in the underground part was washed by immersing the roots in the order of tap water, 0.1M nitric acid and distilled water in order to wash away the components of the hydroponic solution adhering to the roots. The sample in the underground part and the sample in the above-ground part after the washing were sufficiently dried with a heat dryer (105 ° C.) to completely evaporate the water. After measuring the weight of each sample after drying, each sample was pulverized using a pestle and mortar. Thereafter, using a microwave decomposing apparatus (ETHOS-1600, Milestone General Co.), organic substances contained in each sample that could be an interfering substance when measuring the amount of heavy metal elements were decomposed. This decomposition operation was performed by adding 5 ml of nitric acid and 1 ml of hydrogen peroxide water to about 0.3 g of each crushed sample (the total amount when the total weight is 0.3 g or less). The recovered decomposition solution was made up to a volume of 10 ml using a measuring flask.

The zinc concentration of the collected liquid was measured with an ICP emission analyzer (IRIS Advantage ICAP, Nippon Jarrell Ash). The zinc content contained in each plant was calculated from the measured value of the zinc concentration in the sample liquid and the weight of the sample used for the measurement.

Fig. 1 shows the zinc concentration in the above-ground part of rape in each treatment area. Compared to the zinc content accumulated in the plants in the control group not coated with glutathione, the rapeseed in the glutathione-treated group (GSH-treated group) fed with glutathione only in the leaves increased its zinc content by about 5 times. It was increasing. In this experiment, the cadmium content accumulated in the plant did not increase as much as the zinc content. In addition, the standard amount of zinc of Komatsuna in the figure is based on Non-Patent Document 3. From the zinc content contained in 100 g of Komatsuna leaves listed in the food composition table 2010, the water content in Komatsuna leaves was estimated to be 90%, and the zinc content per 1 g of Komatsuna dry matter weight was calculated. This value is shown for comparison with the measured values of the examples. (Non-Patent Document 4)

As mentioned above, rape was used as the target plant. However, since plants belonging to the same family are expected to have similar nutritional characteristics, the technology of the present invention can be applied to cruciferous plants such as cabbage and Chinese cabbage. Of course. Further, since the amount of zinc accumulated in the leaves has increased, the same effect can be expected for the amount of zinc accumulated in the grain.

Further, although glutathione is used here, it is also possible to use a compound having a thiol group such as cysteine. Further, in this experiment, the application to the leaves was performed with a brush, but it is needless to say that the application may be performed with a spreader. Of course, it is possible to add the glutathione solution as it is or to a foliar spray.

Zinc content in rape leaves treated with glutathione

By adding the substances described in the claims to the foliar spraying agent, etc., the amount of zinc accumulated in the stems and leaves of individual crops can be easily increased. As a result, it is possible to stably provide high value-added crops containing zinc at a high concentration to the market. The present invention can greatly contribute to the promotion of agriculture. In addition, the present invention can be applied to not only ordinary soil cultivation but also hydroponics, so that it can be used in plant factories and the like, and enables safe and high-value-added crop production. To do.

Claims (3)

A foliar spray agent to which a glutathione solution containing reduced glutathione having a pH adjusted to be equivalent to that of a plant apoplast is added. A foliar spray characterized by promoting increased zinc accumulation in the grain part. The foliar spray agent according to claim 1, wherein the plant body according to claim 1 is a cruciferous plant including rape, cabbage, Chinese cabbage and the like. A method for increasing and promoting the accumulation of zinc in a stem, a leaf, or a grain part of a plant using the foliar spray agent according to claim 1 or 2.