AU2659884A - Development of plant roots - Google Patents

Description

-1- DEVELOPMENT OF PLANT ROOTS

Cross-Reference to Related Application

This is a continuation-in-part of Application Serial No. 470,392, filed February 28, 1983.

Background of the Invention

Agrobacteriuπ. rhizogenes is the causal organism of what has been termed "the hairy root disease" in a number of species of higher plants. A. rhizogenes can be isolated from the soil, and is a species of agrobac- teriu which has the following characteristics: aerobic, rod-shaped (0.8 x 1.5-30 micron), one to four peritri- chous flagella, Gram negative, and nonspore forming. The common species are A. tumefaciens, which is tumor-causing; A. rhizogenes, which causes hairy-root disease; and A. radiobacter, which is nonpathogenic.

The potential of using A. rhizogenes to the benefit of man was mentioned in an article entitled, "Studies on Infectious Hairy Root of Nursery Apple Trees," Journal of Agricultural Research, Vol. 41, No. 7, pp. 507- 540, A. J. Riker et al. The authors state at 537, "In preliminary experiments cuttings or layers of certain plants treated with the hairy-root organism have rooted sooner and more vigorously than those untreated. These results suggest the possibility of using this organism -2- to stimulate root production in the propagation of cer¬ tain plants. More work is necessary before conclusions can be drawn." Despite this invitation^', A. rhizogenes has not been actively pursued to the benefit of man, and remains regarded as an undesired pathogen.

Summary of the Invention

' It has now been found that one can effectually cause the controlled beneficial growth of roots in dicotyledon- ous plants by genetic transformation with root-inducing . rhizogenes, preferably a novel strain designated as Agrobacterium rhizogenes ATCC 39207. The control exists in that functional A. rhizogenes has or exhibits an undesired potential to contaminate soil, either can be effectively controlled by the use of Agrobacterium radiobacter, preferably ^. radiobacter K-84, used in con¬ junction with or following genetic transformation of the plant with A. rhizogenes. Independent of which PL . rhizo¬ genes is used, a plant is transformed by contact of the exposed pericycle of the plant with A. rhizogenes in an aqueous suspension or other medium, such as peat, prefer¬ ably at an effective concentration of at least about 10⁸ cells per ml, for a period of time to achieve transforma¬ tion. Uniform results are obtained by an exposure of at least about 20 hours. The presently preferred exposure for the stated concentration is at least about 24 hours. Irreversible transformation occurs. Any A. rhizogenes then remaining on the surface of the plant is superfluous to root development. It can therefore be reduced to non- infective levels by exposure to A. radiobacter. A simple dip is all that is required in an aqueous suspension in which the A. radiobacter concentration is from about 10^*7 to about 10⁹ cells/ml. Conveniently, it has been found

OMPI -3- that transformation may be accomplished by combining A. rhizogenes with A. radiobacter in the same treating solutions, in a cell ratio of at least about 4 to 1, preferably from about 4 to 1 to about 8 to 1 A. rhizogenes to A. radiobacter. Presently preferred solutions contain about 10^ cells" of A. rhizogenes and about 2.5 x 10⁸ cells of A. radiobacter per ml. Contact, again-, is for at least about 20 hours. . With such treat¬ ment, A. radiobacter renders the surplus A. rhizogenes innocuous.

In either event, both A. rhizogenes and A. radio¬ bacter, alone or in combination, will withstand pelle- tizing by centrifugation and lyophilization to yield dry, viable cells. In addition, they may be, and pre- ferably are, supported by other media such as neutral to alkaline peat to be used directly by application to the receptive zone of the plant for the prescriptive period of time or from which the organism(s) are extracted for use in aqueous solution. A. rhizogenes ATCC 39207 has been established to be more effective than its source for root development exhibiting the potential of doubling root growth in the same amount of time.

OMPI ___.4_

Brief Description of the Drawings

FIG. 1 is a photo of a control North Star cherry tree taken 45 days after planting, illustrating the degree of leaf development.

FIG. 2 is a photo of a transformed North Star cherry tree taken 45 days after planting, illustrating the increased leaf development.

FIG. 3 illustrates carrot disks cut from the same carrot. With reference thereto, disk 10 is a control as was not transformed. Disks 12 and 14 were transformed with A. rhizogenes TR 105. Disk 16 was transformed with A. rhizogenes ATCC 39207.

-5-

Detailed Description

According to the present invention,^' there is pro¬ vided a novel strain of A. rhizogenes, namely, A. rhizo¬ genes ATCC 39207, which was isolated from A. rhizogenes TR 105, which may be used alone or in combination with other root-inducing A. rhizogenes for genetic transforma¬ tion of dicotyledonous plants to enhance root development, with control of the A. rhizogenes being available through the use of A. radiobacter, preferably A. radiobacter K-84.

A plant genetically transformed with A. rhizogenes may be subsequently treated with A. radiobacter or the two combined, to achieve transformation. In the process, A. radiobacter renders surplus A. rhizogenes innocuous. If the two are combined, they may be combined in a cell ratio of about 4 to 1 or more A. rhizogenes to A. radio¬ bacter, preferably from about 4 to 1 to about 8 to 1, with A. radiobacter serving to substantially prevent the A. rhizogenes contaminating the soil without interfering with plant transformation. Transformation of a plant with A. rhizogenes in all cases requires exposure to the pericycle, since the organism is noninvasionary. Expo¬ sure is for a time sufficient for genetic transformation to occur. It is presently preferred that effective exposure to transforming A. rhizogenes be for at least about 20 hours, preferably at least about 24 hours. Transformation generally requires exposure of A. rhizo¬ genes to a wound of the plant, either created by means of a cut (whether or not new) or simply through severed roots. A. rhizogenes concentration in a treating medium is normally at least least about 10⁸ cells/ml, preferably at least about 10⁹ cells/ml. Lower concentrations are also useful but may require longer exposure for trans¬ formation to occur. It may be provided as an aqueous solution or through a carrier, such as peat, which is -6- brought into contact with the receptive, exposed surface of the plant, and from which transformation occurs by cell diffusion. In the alternative, the contained organism(s) may be extracted from the peat into an aqueous solution used for transformation of the plant.

Benefits of the use of A. rhizogenes in accordance with the instant invention are many. It may be employed, first- of all, to promote early rooting of bare-root stock, leading to more leaf development, both in size and number; less die-back of limbs and stems; an increase in oppor¬ tunity for fruit development during first-season planting; reduced pruning of the tree prior to planting; and, signi¬ ficantly, increasing the potential of the plant to survive drought. The same benefits may be induced to plant cut— tings, where cut stems are placed in mist benches until sufficient roots develop. In this instance, more root development per unit of time can be expected by practice of the instant invention. The invention may also be em¬ ployed in transplanting of larger plants, such as trees, which are well-known to undergo shock during the process of transplanting. Transformation with 2 rhizogenes through cut roots can be used to promote rapid develop¬ ment of new roots at locale of root cleavage, allowing adequate moisture take-up by the tree to prevent leaf- drop and tree death. In essence, treatment can be used to enhance plant vigor.

Finally, plants suffering from root damage or disease may also be benefited by treatment with A. rhizogenes to promote the rapid development of new root growth to counteract those undergoing degeneration.

Despite the potential benefits of the invention, A. rhizogenes may remain regarded as a soil pathogen. In this instance, its effect can be eliminated or diminished to noninfective levels through the use of A. radiobacter. A. radiobacter K-84 is presently preferred. A. radiobacter K-84 is cultured and sold by AgBioChem, Inc. ,

OMPI -7- 3 Fleetwood Court, Orinda, California 94563. One can simply dip the transformed plant into an aqueous solution of A. radiobacter, preferably present in a concentration in excess of about 10⁷ cells/ml, for but seconds to effectively terminate the active A,, rhizogenes.

More conveniently, the two may be combined in a com¬ mon transforming medium. When present in a cell ratio of A. rhizogenes to A. radiobacter of at least about 4 to 1, preferably from about 4 to 1 to about 8 to 1, transforma- tion can occur without leaving a residue of active A. rhizogenes on the plant. In this instance, as in the instance of the use of A. rhizogenes alone, transforma¬ tion requires exposure of a receptive plant area to the transforming organism. However, the A. radiobacter does not appear to interfere with the transformation process. Peat has been found to be an excellent host for the organisms. Organisms have been found to thrive in essen¬ tially neutral to alkaline (pH) peat, which serves as a convenient carrier and an effective treating medium. Lyophylization can also be employed. If peat is employed, the A. rhizogenes is kept separate from the A. radiobacter and the peat units carrying them are combined at the time of use.

Without limitation, the following illustrate the invention. In connection with plantings in ground, plantings, unless otherwise indicated, were made during the normal planting season for the 45th parallel for the State of Montana, United States of America.

Examples 1 to 4 and Controls A to D

Bare-root plum trees averaging from 4 to 5 feet in height, were root-wounded, then treated with A. rhizo¬ genes TR 105, provided by Dr. Nester, Department of Microbiology and Immunology, University of Washington, Seattle, Washington 98195, by submersing the wounded area

OMPI -8- of the plant into a solution containing A. rhizogenes at a cell-suspension concentration of about 9 x 10⁹ cells per millimeter for 24 hours. The control roots were submerged in water alone. Treated and control stocks were stored at 40°F until time for planting, and were then planted in a soil/ver iculite 1:1 mix in the field. The trees were watered every three days for nine days, then natural rainfall was relied upon for root develop¬ ment. After a period of about 30 days, the plants were gently removed from the soil and rinsed with water. The new roots were picked, with the aid of tweezers, from the old roots, then dried and weighed. The results are shown in Table I.

Table : I

New Root Weight

Transformed

Example Plant (q) Control ⁽g⁾

•

1 .025 A .004

2 - .018 B .009

3 .019 C .014

^ .012 D .006

x .019 x .008

Significant difference is at the 0.1 level

Examples 5 to 8 and Controls E to H Other plum trees from the same source as those used for Examples 1 to 4 and Controls A to D were treated in the same manner, but measured for leaf development. The measurements were respectively taken at the end of mid¬ summer and about two weeks later. The results are shown in Table II.

O PI -9-

Table ^'II

Leaf Development

Transformed Plant Leaf

Leaf Size No. of Size No. of

Example (cm) Leaves Control (cm) Leaves

5 3.919 length 155 E 2.028 length 53

2.725 width 1.740 width

6 4.183 length 170 F 1.920 length 104

- 2.253 width 1.680 width

7 5.124 length 113 G 2.529 length 115 4.001 width 2.109 width

8 4.501 length 158 H 2.348 length 147 4.173 width 2.440 width

Total 596 419

All differences between treatments and controls are significant at the 0.01 level.

Examples 6 to 11 and Controls I to K North Star cherry trees averaging about 4 feet tall taken from bare-root stock were root-wounded for both the treatment and controls. Following the procedure of Exam¬ ples 1 to 4, injured roots were transformed with a solu¬ tion containing about 1.6 x 10¹⁰ cells of A. rhizogenes TR 105 per milliliter, soaked overnight, and left in dark, cold storage for 18 days. Planting occurred early in the planting season. The transformed plants blossomed five days after budding. It took the controls an addi¬ tional 10 days to blossom. Approximately 45 to 50 days after planting, cherries were observed on the transformed plants, and a leaf, stem and cherry count was made in mid¬ summer. With significant difference at the 0.05 level, -10- the comparison of transformed to control, the number of leaves, number of cherries, number of branches, die-back and leaf length were observed, as reported in Table III. FIG. 1 is a photo of control plant about 45 days after planting. FIG. 2 is a photo of a transformed plant which has been exposed to the same growth conditions as those of the plant shown in FIG. 1, except for the use of A. rhizogenes to promote root growth.^" In addition to the apparent differences, there was also more root spur forma¬ tion, which is indicative of higher flower and root development in the following years of growth.

Table III

No. of No. Of

No. of Ripened Branches Leaf

•Leaves Cherries Died Back Length (cm)

Example #9 590 3 6/13 6.5

Example #10 707 9 5/14 6

Example #11 593 0 1/07 6

Control I 0 0 15/15 -

Control J 351 ^• 0 10/16 4.5

Control K 374 0 6/10 2.5

In a following growing season, treated plants yielded several times the amount of cherries as did untreated or control trees.

Example 12 and Control L A. rhizogenes ATCC 39207 was derived from Agrobac¬ terium rhizogenes TR 105 by screening isolated single colonies of TR 105 on carrot root disks until a change was observed in the degree of root development. A treating solution was made of Agrobacterium rhizogenes TR 105 to a to a cell concentration of 2.1 x 10⁹ cells per milliliter, and a comparison solution of A. rhizogenes ATCC 39207 at a cell concentration of 4 x 10⁹ cells per

OMPI - 11- milliliter. Carrot disks were treated at a concentration of 0.1 milliliter per carrot disk and incubated for three weeks at room temperature. The results^' of the degree of root formation are shown in Table IV and illustrated in Fig. 3, explained at page 4 herein.

Table IV

Carrot i n Carrot #2 Carrot #3 Carrot #4

A. -rhizogenes TR 105

.0025 .0054 .0000 .0006

.0010 .0015 .0060 .0003

.0011 .0009 .0037 .0016

.0030 .0027 .0020 .0016

.0043 .0015 .0003 .0009

.0076 .t)027 .0017 .0009

.0030 .0001 .0034 .0001

.0053 .0044 .0042 .0012

. .0030 .0046 .0013 .0016

.0096 .0021 .0047 .0005 x .0040 .0026 .0027 .0009

A. rhizogenes ATCC 39207

.0024 .0000 .0001 .0000

.0101 .0003 .0015 .0013

.0036 .0010 .0022 .0003

.0113 .0012 .0007 .0006

.0118 .0063 .0012 .0005

.0093 .0018 .0035 .0027

.0078 .0004 .0058 .0002

.0123 .0034 .0019 .0031

.0127 .0035 .0011 .0010

.0006 .0059 .0051 .0002

_ x .0082 .0024 .0023 .0010 Data x for Carrot #1 are different TR 105 from ATCC 39207 at 0.05 level. In the above work, cell density was about 130 cells per square inch of carrot-disk surface. -12- If a plant has the potential of being an excellent rooter, A. rhizogenes ATCC '39207 will at least double the dry weight of roots; otherwise, no difference is shown. A. rhizogenes ATCC 39207 is on viable deposit at the America Type Culture Collection, 12301 Parklawn Dr.,

Rockville, Maryland 20852, and was initially given the identification Agrobacterium rhizogenes MT 232 by me.

Example 13 and Control M Avocado-stem cuttings 10-12 cm in length were used for the control (80 test plants) and for transformation (100 test plants). To transform the plants, the cuttings were dipped in a suspension containing A. rhizogenes TR 105 at a concentration of 10⁹ cells/ml for 15 minutes. This insured inoculation with sufficient cells to achieve transformation. The cuttings were planted in a rooting mixture of 40% by weight perlite and 60% by weight peat. The cuttings were placed on a cloud 9 fogging system mist bench, and every 10 minutes the mist was applied^'during daylight hours only (16-hour days). Two months after planting, it was determined that 5 of the 80 control plants were alive and had produced leaves and roots, while 61 of the 100 transformed plants were alive and had produced leaves and roots.

Example 14 and Control N The following is to-establish that A. rhizogenes is effective in promoting root development in plants that are vegetatively propagated. Cuttings of stems with leaves of violets were dipped into a suspension of A. rhizogenes at a concentration of about 10⁹. cells per milliliter, and were placed on the mist bench until root¬ ing occurred. In this instance, the control plants gave an average of 0.002 grams dry weight of root development er plant, whereas transformed cuttings gave an average -13- of 0.005 gram of roots per plant on a dry-weight basis. This is a significant difference at the 0.1 level. The observations were made two weeks after placement on the mist bench, and are shown in Table V.

Table V: DRY WEIGHT OF ROOTS PRODUCED ON VIOLET-STEM CUTTINGS

Control N Example 14

.0015 .0043

.0042 .0038

.0011 .0040

.0054 .0063

.0002 .0030

.0020 .0028

.0010 .0036

.0022 .0034

.0014 .0103

.0012 .0026

.0012 .0054

.0004 .0064

.0025 .0056

.0023 .0086

.0028 .0050 χ= .0020 x= .0050

Example 15 and Control O Mango cuttings of approximately 10 cm. in length were transformed by dipping the lower 7 cm. into a bac¬ terial suspension containing 7 x 10^$ cells of A. rhizo¬ genes per milliliter. Forty mango cuttings were used for each test. The transformed cuttings and controls were placed on the mist bench and maintained at 70-80°F. In the case of the controls, 41.0 4^7.5% of the cuttings developed plants, whereas the A. rhizogenes-treated cuttings had 79% +7% develop into plants.

OMPI -14-

Example 16 The procedure of Examples 6 to 11 and control for North Star cherries was repeated^' in the next growing season. It gave similar results. The treated trees of Example 16 gave several times the amount of cherries as the untreated controls, as shown in Table VI.

Table VI

Controls Treated

20 113

28 61

0 161

Example 17

For this example, selected almond plants were bare- root stock measuring about 1.0 cm. dia. at 20 cm. above ground level. Stem lengths were about 40 cm. Treated and untreated plants (control) were planted during May 13-17, and were watered every 10 days for 4 hours at the rate of 2 liters/hour, for a total of 20 liters/plant. Watering was increased ten percent each month. The fertilizer employed was 6%N, 6%P, 6% K + microelements applied at a concentration of from 50-100 ppm in each watering. No pesticides were applied.

Two to three months after planting, measurements were made of: the trunk diameter at 20 cm. above ground level; the number leaves/plant; and the length of new branches (averaged in groups of 5). Twenty to twenty- five trees were used per determination in Table VII.

OMPI

^ WIPO ΛATI -15-

Table VII

Leaf Trunk New Stem

Count Diameter Length

Treated 1049 +_134 1.8 +0.19 64 +8.4 Control 622 +_134 1.4 +0.17 41 +_8.1 All differences between treatments and controls are significant at the 0.001 level.

Example 18 One year and 4 months after planting of plum trees, as described in Examples 1-8, attempts were made to col¬ lect A. rhizogenes from the rhizosphere and rhizoplane of plum trees that had been inoculated with A. rhizogenes at the time of planting. Samples of soil were taken^'from the root zone of each tree and plated on an Agrobacterium- selective medium. After 2 days at 27°C, 8 different areas from each plate showing bacterial growth were applied to carrot disks. Thus, the soil from each tree had 16 samples (8 rhizosphere and 8 rhizoplane). After 2 weeks the disks were checked for rooting.

The soil from 4 untreated trees (controls), when placed on the selective medium, yielded organisms capable of producing the rooting syndrome on carrot disks. A total of 72 tests were run: 36 tests from the rhizosphere sphere and 36 tests from the rhizoplane. In the inocu¬ lated trees, 3 of 5 gave an indication of _A. rhizogenes. In one case, 3 of 8 disks from the rhizosphere of one tree were positive, whereas the rhizoplane soil was negative. In the other tree, 6 of 8 carrot disks were positive from the rhizosphere, and 3 of 8 were positive from the rhizo¬ plane. In another case, 1 of 8 rhizoplane samples was positive. -16- Thus, although A. rhizogenes is recoverable from the root zone of previously inoculated plants, it seems relatively confined to the rhizosphere soil (that which is attached to the root surface) . Because of task diffi- culty, numbers of infectious bacterial cells/gram soil was not determined.

A procedure was then carried out to determine -if there were enough A. rhizogenes present in the root zone to infect a fleshy, rooted host plant (carrot) of A. rhizogenes. At the end of May, carrot seeds were sown

10-100 cm. from the main stem of both treated and control trees. At the beginning of September, carrots were care¬ fully removed from the soil and rinsed in water. The results are shown in Table VIII.

Table VIII

Treated Control

Without With Without With ^• Hairy Root Ha:Lry Root Hairy Root. " Hairy Root

96 0 63 0

73 0 40 0

27 0 22 0

53 0 57 0

55 0

The results suggest that, A. rhizogenes, having been, inoculated onto the roo'ts of plum trees in one season, is present in and around the roots of some trees in the second season, but not in sufficient quantity to infect the roots of a normally susceptible, fleshy, rooted plant, namely, carrot. -17-

Example 19 and Control P A. rhizogenes ATCC 39207 in a 4-to-l weight-to-weight admixture with A. radiobacter, in an aqueous slurry of 1 gram of the mix per 10 ml. water, was used to root pepper plants (Yolo Wonder). The plant root systems were washed and placed in the transforming slurry for a period of one hour prior to planting in the field. Table IX shows the observations made for 5 plants, 46 days after planting. Early high yield of peppers over 5 cm. long, provides an early-to-market economic advantage.

Table IX

Control

Weight of Root Stem Number of Total

Plot Volume Diameter Total Peppers Over Peppers Number per ml.l per mm.2 Peppers^ 5 cm. Long (in gms.)

1 33.00 40.0 5 0 29.0

4 52.00 56.0 5 4 125.0

5 42.00 49.0 7 2 91.0

8 39.30 49.0 3 1 18.5

Totals per 5 Plants: 166.30 194.0 20 7 263.5

Average per Plant: 8.32 9.7'

&JREA,

OMPI WIPO _<tv -18- Table IX, continued. . .

Treated

Weight of

Root Stem Number of Total -

Plot Volume Diameter Total Peppers Over Peppers

Number per ml.l per mm. 2 Peppers^ 5 cm. Long (in gms. )

2 50.0 53.0 19 8 266.0

^'3 52.0 56.0 12 9 379.0

6 42.0 46.0 3 2 121.0

7 62.0 63.0 5 2 87.0

Totals per 5 Plants: 206.0 218.0 39 21 853.0

Average per Plant: 10.3 10.9

With a total of ten plants per plot, the observations reported in Table X were ^"made at the number of days after planting as indicated in Table X. By final harvest, the control plants, in weight yield, had caught up to the transformed plants.

1) Obtained by displacement of washed root system in water.

2) Measurement taken just above first raised ring above root system.

3) All peppers collected from plants sacrificed for root-development examination. -19-

Table X

(10 Plants per Plot)-

Control

Harvest Days: 53l 122¹ 132² t. No. Wt. - No. Wt. No.

Plot (lbs.) Peppers (lbs.) Peppers (lbs.) Peppers

1 2.06 18 2.44 16 2.0 14

4 1.37 9 3.0 21 2.13 22

5 1.37 10 5.0 20 1.0 10

8 1.20 10 2.69 15 1.06 30

Treated

2 2.31 19 _.3.0 17 1.56 20

3 1.50 14 4.13 18 1.56 16

6 1.69 11 2.31 12 1.25 14

7 .8 . 8 3.94 19 2.50 45

Totals

Control Treated

Weight No. Weight No.

Plot (lbs.) Peppers Plot (lbs. ) Peppers

1 6.5 48 2 6.87 56

4 7.5 52 3 7.19 48

5 7.37 40 6 5.25 37

8 4.95 55 7 7.24 72

Grand Grand Total 26.32 195 Total 26.55 213

) Only peppers of marketable si ze harvested ( 2.5" or longer) . ) Al l peppers harvested assuming k i l l i ng frost on 10/13-14/83.

_ OMPI -20-

Example 20 Experiments involving tea roses, cabbage, flavoring tobacco, and crysanthemums, gave inconclusive results. Lilacs, however, were.responsive, with results as shown in Table XI. (Significant at 0.14.)

Table" XI

Control Treated

(total leaves) (total leaves)

39 151

124 109 >9 170

Totals 262 430

.Example 21 The longevity of A. rhizogenes ATCC 39207, when pre¬ pared in peat and stored at 23 +3°C, was determined. Viable cell count per gram of peat, with time, is shown in Table XII.,

Table XII

A 1.5 Months 3 Months 10.5 Months

Prepared Later Later Later

3.1 x 10⁸ 2.7 x 10⁹ 1.1 x 10⁹ 2.0 x 10⁷

-21-

Exa ple 22 Some olive plants of bare-root stock, 30 cm. in stem height and 0.60 cm. in diameter at 5.0 cm. above soil level, were transformed using A. rhizogenes ATCC 39207. Others served as controls. All were planted in the desert in June, and were watered and fertilized in accordance with Example 17. Six months after planting, the measure¬ ments shown in Table XIII were taken.

Table XIII

Stem Diameters (in c . )

Controls Treated

0.91 1.64 2.05

1.27 1.17 2.00

1.25 1.88 2.00

1.40 1.59 1.65

1.35 2.00 1.50

1.30 1.55 2.20

1.42 1.70 1.35

Lengths of Longest Four Side Limbs (in cm.^'

60,50,70,40 70,75,68,72 95,78,86,100 60,48,67,68 65,58,78,72 85,95,78,80 62,50,42,45 110,80,78,94 130,110,120,100 65,55,75,81 100,110,90,88 110,100,90,80 40,25,30,35 75,80,82,90 90,80,70,70 70,60,55,45 100,90,100,95 100,110,90,80 65,60,40,45 70,80,72,85 100,100,90,80

OMPI

^NATIO^ A. rhizogenes ATCC 39207 will be made available as of the first publication of this specification. It can be streaked onto plates containing a nutr-ient agar formed from 3 grams bacto-beef extract, 5 grams bacto-peptone, and 15 grams bacto-agar, with sufficient distilled water added to form 1 liter. The mixture is autoclaved prior to use.

The same solution, free of agar, is a nutrient medium for colony growth. The colony is deposited after auto- claving. The flask is shook at 140 rp at 24°-26°C.

About two days are required to reach log growth phase. Normal cell density is about 10⁹ cells/ml.^"

Claims (15)

WHAT IS CLAIMED IS :

1. Agrobacterium rhizogenes ATCC 39207 ,

^•5

2. A composition for the genetic transformation of dicotyledonous plants for the beneficial growth of roots which comprises:

(a) root-inducing A. rhizogenes provided in a 10 concentration sufficient to provide an aqueous suspension of cells in a concentration sufficient to genetically transform a dicotyledonous plant to enhance root growth; and

(b) A. radiobacter in an amount sufficient to 15 render the A. rhizogenes substantially noninfective.

3. A composition as claimed in claim 2 in which the A. rhizogenes and the A. radiobacter are contained as separate units, with at least one being present in peat. 0

4. A composition as claimed in claim 2 or 3 in which the root-inducing A. rhizogenes is present in a concentration sufficient to provide an aqueous suspension of cells thereof, of at least about 10⁷ cells/ml, and 5 A. radiobacter is present in a concentration in cells per milliliter such that cell ratio of A. rhizogenes to A. radiobacter is at least about 4 to 1.

5. A composition as claimed in any one of claims 0 2 to 4 in which the cell ratio of A. rhizogenes to A. radiobacter is from about 4 to 1 to about 8 to 1.

6. A composition as claimed in any one of claims

2 to 5 in which the A. rhizogenes comprises A. rhizogenes 5 TR 105 and in which the A. radiobacter comprises A. radiobacter K 84.

iJRE i

OMPI_

7. A composition as claimed in any one of claims 2 to 5 in which the A. rhizogenes comprises A. rhizogenes ATCC 39207.

^•5

8. A composition as claimed in claim 7 in which the A. radiobacter comprises A. radiobacter K 84.

9. A process for- genetically transforming

10 dicotyledonous plants which comprises contacting roots of the dicotyledonous plant having exposed pericycle to the transforming action of root-inducing A. rhizogenes for a time sufficient to transform the dicotyledonous plant for enhanced root growth, and contacting the plant with

15 A. radiobacter for a time sufficient to render the A. rhizogenes substantially noninfective.

10. A process for genetically transforming dicotyledonous plants which comprises contacting 0 roots of the dicotyledonous plant having exposed pericycle to the action of A. rhizogenes in a medium in which root-inducing A. rhizogenes is present in a concentration equivalent of an aqueous suspension of at least 10⁸ cells/ml for at least about 20 hours and

25 sufficient to genetically transform the dicotyledonous plant and enhance root growth, then contacting the plant with A. radiobacter present in a medium in which the concentration of A. radiobacter is present in a concentration equivalent a suspension of about 10⁷

30 cells/ml for a time sufficient to render A. rhizogenes substantially noninfective.

11. A process as claimed in claim 10 in which contact with A. rhizogenes is for at least about 24 hours.

12. A process as claimed in any one of claims 9 to

11 in which the A. rhizogenes comprises A-. rhizogenes TR 105 or A. rhizogenes ATCC 39207.

^■5

13. A process as claimed in any one of claims 9 to

12 in which the A. radiobacter comprises A. radiobacter K-84. ^•

10 14. A process as claimed in any one of claims 9 to

13 in which the medium is aqueous and the A. rhizogenes and the A. radiobacter are contained in an aqueous suspension and in which the cell ratio of A. rhizogenes to A. radiobacter is from about 4 to 1 to about 8 to 1.

15

15. A process as claimed in any one of claims 9 to 14 in which the A. rhizogenes and the A. radiobacter are provided as separate units, at least one of which is provided in peat. 0

5

0

5

OMPI