Triploid watermelon plants with a bush growth habit

Abstract

The application relates to the field of plant breeding, in particular watermelon breeding. Provided are bush type, triploid watermelon plants (and seeds from which these plants can be grown) and seedless watermelon fruits produced by these plants. Also provided are bush type pollenizer plants and bush type tetraploid plants and methods for producing triploid hybrids having a bush growth type, as well as methods for producing seedless watermelon fruits of high quality.

Claims

1. A plant or a plant part thereof of watermelon line WHAAPD, wherein a representative sample of seed of said plant has been deposited under accession number NCIMB 41905.

2. The plant part of claim 1, wherein said plant part is a scion, fruit, pollen, a cell, a meristem, a cotyledon, pollen, an ovule, a leaf, an anther, an embryo, a root, a root tip, a pistil, a flower, or a stem.

3. A tissue or cell culture of regenerable cells of the plant of claim 1.

4. The tissue or cell culture of claim 3, comprising cells or protoplasts or plant tissue from at least one plant part, wherein said plant part is an embryo, a meristem, a cotyledon, pollen, an ovule, a leaf, an anther, a root, a root tip, a pistil, a flower, seed, or a stem.

5. A watermelon plant regenerated from the tissue or cell culture of claim 3, wherein the plant has all of the physiological and morphological characteristics of watermelon line WHAAPD.

6. A method of producing of watermelon line WHAAPD, or a part thereof, comprising vegetatively propagating the plant part of claim 1.

7. The method of claim 6, wherein said vegetative propagation comprises regenerating a whole plant from a plant part of watermelon line WHAAPD, wherein representative seed of said line has been deposited under Accession Number NCIMB 41905.

8. The method of claim 6, wherein said plant part is a cell culture or a tissue culture.

9. A vegetative propagated plant, propagated from the plant part of claim 6, wherein the vegetative propagated plant has all of the physiological and morphological characteristics of watermelon line WHAAPD.

10. Seed of watermelon line WHAAPD, wherein a representative sample of seed of said plant has been deposited under accession number NCIMB 41905.

11. A method of making a watermelon plant comprising crossing the plant of claim 1 with another watermelon plant.

12. The method of claim 11, wherein the other watermelon plant is an inbred diploid line.

13. A progeny watermelon plant obtained by selling watermelon line WHAAPD, wherein a representative sample of seed of watermelon line WHAAPD has been deposited under accession number NCIMB 41905, and wherein the progeny plant has all of the physiological and morphological characteristics of watermelon line WHAAPD.

14. A triploid watermelon plant made by crossing a tetraploid female parent watermelon line WHAAPD, or a progeny line according to claim 13, with a diploid male parent watermelon line, wherein a representative sample of seed of watermelon line WHAAPD has been deposited under accession number NCIMB 41905.

15. The plant of claim 14, wherein the diploid male watermelon line is an inbred line.

16. Seed of the triploid watermelon plant of claim 14.

17. A method for making a triploid watermelon seed, comprising allowing pollination of pistillate flowers of watermelon line WHAAPD, or a progeny watermelon plant of claim 13, with pollen of a diploid watermelon line, and harvesting seeds produced in the fruits of the watermelon line WHAAPD plant, wherein a representative sample of seed of watermelon line WHAAPD has been deposited under accession number NCIMB 41905.

18. The method of claim 17, further comprising drying the harvested seeds.

19. Seed produced by the method of claim 17.

Description

FIGURE LEGENDS

(1) FIG. 1

(2) Schematic diagram of the methods and plants/fruits according to the invention. A bush male (bb) and bush female (bbbb) are crossed to produce seeds of triploid bush hybrids (bbb). These F1 seeds can be interplanted (in-row or between-row) with any diploid pollenizer to produce triploid seedless fruit on the triploid hybrid bush plants.

(3) The following non-limiting Examples describe the production of triploid bush hybrids according to the invention. Unless stated otherwise in the Examples, methods for conventional watermelon breeding are used, such as e.g. described in Maynard 2001, WatermelonsCharacteristics, Production and Marketing, ASHS Press; Mohr H. C. Watermelon Breeding in Mark J. Bassett (editor) 1986 Breeding Vegetable Crops, AVI Publishing Company.

DEPOSIT INFORMATION

(4) Applicant has deposited hybrid WH3451 at the Dec. 1, 2011 under at the NCIMB under Accession number NCIMB 41907. Seeds of WHAAPD and WHAAOX were deposited by Nunhems B. V. on Dec. 1, 2011 at the NCIMB under Accession numbers NCIMB 41905 and NCIMB 41906, respectively. Access to the deposits will be available during the pendency of this application to persons determined by the Commissioner of Patent and Trademarks to be entitled thereto upon request.

(5) Subject to 37 C.F.R. 1.808(b), all restrictions imposed by the depositor on the availability to the public of one or more deposits will be irrevocably removed upon the granting of the patent by affording access to a deposit of at least 2500 seeds with the NCIMB Ltd., Ferguson Building, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA, UK. The deposit will be maintained for a period of 30 years, or 5 years after the most recent request, or for the enforceable life of the patent whichever is longer, and will be replaced if it ever becomes nonviable during that period. Applicant does not waive any rights granted under this patent on this application or under the Plant Variety Protection Act (7 USC 2321 et seq.).

EXAMPLES

Example 1: Generation of Triploid Bush Hybrids (bbb)

(6) It was observed that a home-garden diploid watermelon had an interesting growth type. Starting from this observation a breeding program was developed in order to determine the heritability of this growth type and in order to fix the growth type, as to be able to generate triploid hybrids having this growth type. The growth type was found to be heritable as recessive trait, and was termed bush allele (b). It was found to be responsible for vine length, without however affecting leaf size or fruit size.

(7) In order to generate a triploid bush hybrid, first an inbred diploid bush male parent line and an inbred tetraploid bush female parent line were generated (see FIG. 1).

(8) Generation of the inbred bush male parent was done by selecting a diploid having the observed growth type, making a number of crosses with said diploid and proprietary lines and inbreeding the derived diploid bush line for nine generations to fix the bush characteristics in the diploid line.

(9) Generation of the tetraploid female bush inbred line was carried out by selecting a diploid watermelon having the observed growth type, making a number of crosses with said diploid and proprietary lines and generating a diploid bush inbred line by selfing a derived line for more than nine generations to get a uniform (inbred) diploid bush line. The generated inbred diploid bush line was then treated with colchicine for chromosome doubling. After colchicine treatment a tetraploid line was selected and the line was selfed for several generations to fix the bush characteristics in the tetraploid line. In each generation of seed increase of the tetraploid line ploidy level was checked using flow cytometry.

(10) The tetraploid inbred female bush (bbbb), designated WHAAPD, and diploid inbred male bush (bb), designated WHAAOX, were cross-pollinated to produce fruits with triploid seeds (bbb), designated WH3451. Seeds of the triploid hybrid WH3451 were harvested from the fruits and deposited by Nunhems B. V. on Dec. 1, 2011 under at the NICMB under Accession number NCIMB 41907. Seeds of WHAAPD and WHAAOX were deposited by Nunhems B. V. on Dec. 1, 2011 at the NICMB under Accession numbers NCIMB 41905 and NCIMB 41906, respectively.

(11) The physiological and morphological characteristics of the triploid bush hybrid WH3451 were analyzed in the Examples below.

Example 2: Comparison of Triploid Bush Hybrids WH3451 to Prior Art Hybrids

(12) 2.1Materials and Methods

(13) A field trial was conducted in Italy (Sant'Agata Bolognese-BO). Seeds were sown on Apr. 7, 2010 and transplanted into the field on May 20, 2010 (100 cm within the row, 250 cm between the rows). The plot contained 10 plants per line.

(14) Ploidy level was determined by flow cytometry.

(15) Mean values were determined for the following characteristics: Leaf length and leaf widths was measured for 1 leaf of 3 plants per line. Number of staminate flowers was counted for 3 plants per line on the flowering date. The mean number of 3 plants was calculated. Mean stem diameter was measured on in the middle of the main stem for 3 plants and the mean was calculated. Maturity: the number of days from flowering to maturity was determined by recording the dates when the 50% of the plants of the plot showed at least 1 female flower and then when the 50% of the plants of the plot had fruits ready to harvest Stem: average number of internodes: the average number of internodes on the longest vine measured on 3 plants per line Stem: average internode length (cm): the measured average internode length (cm) on the longest vine on 3 plants per line Stem: average length of the longest vine (cm): average length of the longest vine (cm) measured 3 plants per line Average fruit weight (kg): mean of the weight of 3 fruits per line randomly harvested from 3 plants at maturity Average fruit length (cm): mean of the length of 3 fruits Average fruit diameter at mid section (cm): mean of the diameter of 3 fruits Fruit: rind thickness (cm) at the blossom end and rind thickness on the side of the fruit was measured for 3 fruit. Rind thickness is measured from the outer edge of the fruit to the boundary between white mesocarp and colored endocarp. Fruit: degree Brix: value is the mean of 1 reading for 3 fruits, collected between the centre and the rind of the fruit; expressed in Degrees Brix () using the K71901 portable refractometer Mod. RLC ATC 0-18% (OPTECH). Sowing seed size length (mm) and widths (mm) mean of the measure of 5 seeds colour: evaluated using the Royal Horticultural Society mini colour chart (rhs.org.uk/Plants/RHS-Publications/RHS-colour-charts)
2.1Results

(16) TABLE-US-00001 TABLE 1 WH3451 cv Milady cv Fashion F1 cv Boston F1 (triploid bush Diploid hybrid- Triploid hybrid- Triploid hybrid- hybrid- normal normal normal invention) growth type growth type growth type Ploidy 3n 2n 3n 3n bush alleles bbb BB BBB BBB Leaf lobes lobed lobed lobed lobed Leaf length (cm) 17.50 12.17 17.13 15.67 Leaf width (cm) 19.50 15.50 17.97 16.30 Leaf colour Dark green Dark green Dark green Dark green (RHS color chart) RHS 137a RHS 137a RHS 137c RHS 137a Number of 6.00 15.50 n.d. n.d. staminate flowers Stem diameter (mm) 9.00 7.00 6.25 5.50 Number of main 2.00 2.50 2.00 2.50 stems at crown Leaf: Degree 4 4 4 5 of secondary leaf lobbing 1 = very weal 9 = very strong Maturity: 27.00 29.00 29.00 32.00 number of days from flowering to maturity Stem: average 13.57 31.36 25.95 36.53 number of internodes Stem: average 7.00 11.00 11.00 9.00 internode length (cm) Stem: average 95.00 345.00 279.00 321.00 vine length (cm) Ratio: 7.00 11.00 11.00 9.00 vine length/ number of internodes Average fruit 5.7 11.40 7.30 6.80 weight (kg) Fruit shape in Broad elliptic Elongate circular circular longitudinal (broad circular) elliptic section Average fruit 24.00 46.75 20.60 23.20 length (cm) Average fruit 19.00 21.25 22.25 24.55 diameter at mid section (cm) Fruit index: 1.26 2.20 0.93 0.95 length/ diameter ratio Fruit rind pattern striped striped striped striped Fruit: width of 5 6 2 2 stripes 1 = very narrow 9 = very broad Fruit: Ground Medium green Medium green Dark green Light green color of skin RHS 145b RHS145c RHS 136a RHS 2d (RHS color chart) Fruit: stripe Dark green Dark green Dark green Dark green color (RHS RHS 136a RHS 137a RHS 137c color chart) Fruit: rind 1.50 1.00 1.00 1.30 thickness (cm) (blossom end) Fruit: rind 2.00 2.00 1.50 1.50 thickness (cm) (side) Fruit: Flesh Dark Red Dark Red Dark Red Dark Red color (RHS RHS 44a RHS 45a RHS 44a RHS 47a color chart) Fruit: degree 12.00 11.00 12.00 11.75 Brix Sowing seed size 2 4 4 5 1 = very small, 9 = very large Sowing seed 5.00 8.00 7.00 8.00 size length (mm) Sowing seed 3.00 5.00 5.00 5.00 size width (mm)

(17) The male (bb) and female (bbbb) bush parents have essentially the same bush growth type characteristics as indicated for the triploid hybrid WH3451 in Table 1 above.

Example 3: Reduced Spacing for Triploid Bush Hybrids

(18) As the triploid bush hybrids are small plants, without however having reduced fruit size and fruit yield per hectare and without having reduced leaf sizes (i.e. photosynthetic tissue), these plants can be used to grow at least about 1.5 times, preferably at least about 2 times or 2.5 times, preferably even about 3 times as many triploid plants per hectare compared to normal-type triploid hybrids, such as Fashion F1 and Boston F1, thereby increasing marketable fruit yield per hectare. Thus, the triploid fruit yield per hectare can be increased significantly using the triploid bush plants according to the invention, i.e. fruit yield from triploid bush plants can be at least about 1.25 times or at least about 1.5 times the yield of a normal type triploid production field.

(19) The following Table 2 shows the number of plants per hectare for the normal growth type triploid varieties Fashion F1 and Boston F1 compared to the triploid bush plants according to the invention, such as WH3451:

(20) TABLE-US-00002 Grafted Non-grafted Grafted open Non-grafted greenhouse greenhouse field open field cv Fashion F1 2500 5000 3000 7000 or Boston F1 plants/ha plants/ha plants/ha plants/ha Triploid bush 7500 15000 6000-8000 12000-150000 hybrid plants/ha plants/ha plants/ha plants/ha

(21) Fruit yields for Fashion F1 and Boston F1 are about 60 tonnes/hectare (t/ha) in the open field compared to about 75-90 t/ha for the triploid bush hybrid.

Example 3

(22) In 2012 the vegetative growth type of the male (bb) and female (bbbb) bush parents was determined, the results of which are shown in Table 3.

(23) TABLE-US-00003 TABLE 3 NCIMB41905 NCIMB41906 (tetraploid bush) (diploid bush) Ploidy 4n 2n bush alleles bbbb bb Leaf lobes lobed lobed Leaf length 13.00 14.00 (cm) Leaf width 15.00 10.00 (cm) Leaf colour Dark green Dark green (RHS color RHS 137c RHS 137c chart) Stem: average 6.00 6.00 internode length (cm) Stem: average 133.00 150.00 vine length (cm) Ratio: 6.00 6.00 vine length/ number of internodes