Cultivars (Early PInk, Kyoryoku Toko, Sekaiichi and Giban No. 1) as female parents were diallel-crossed with Lycopersicon peruvianum (PI128652 and P1270435) and L. per. var. glandulosum (PI128644) as male parents. Immature ovules taken from colored fruits were washed through tap water and then treated with a 2% sterile antiformin for about 7 minutes and again washed in sterilized water. Out of them, the ovules, which appeared to be capable of germination according to the characteristics described by Imanishi (1988), were selected in order and plated onto MS agar medium without plant hormones. The efficiency of the visual selection of ovules was highly remarkable in the crosses of Early Pink or Kyoryoku Toko x wild species (Table 1). In the case of Sekaiichi and Giban No. 1, the ovules which appeared to be capable of germination were very few. Early Pink as a female parent was the highest in crosscompatibility with wild species followed by Kyoryoku Toko. Giban No. 1 yielded no ovules that germinated. PI128644 was higher than PI128652 and PI270435 in the cross-compatibility with Early Pink and Kyoryoku Toko. PI270435 seems to have the lowest cross-compatibility with cultivars (Table 2).
Hybrid plants were determined by the ability of shoot-formation. Leaf segments of young leaves of the hybrid plants maintained in vitro were cultured on MA agar medium supplemented with 1.0 mg/1 BA and shoots induced were counted 20 days after initial culture. Forty-three hybrid plants tested were found to be true hybrid ones. Embryos were dissected from the ovules, which appeared to be capable of germination, of the cross of Early Pink and PI128644 and classified into four groups (Table 3). Most of the embryos belonged to Groups C and D.
Literature cited:
Imanishi, S. 1988. Efficient ovule culture for the hybridization of Lycopersicon esculentum and L. peruvianum, L. glandulosum. Jap. J. Breed. 38:1-9.
Table 1: Visual selection and germination of immature F1 ovules
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Visual selection and germination
Cross No. of ovules _________________________ Total ovules
in fruits No. of ovules No of ovules germinated
incubated that germinated
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EP1 x PI 128644 3489 59 38 43
EP x PI 128652 4304 60 25 28
EP x PI 270435 6935 101 27 27
KT2 x PI 128652 6422 100 8 12
KT x PI 128652 4422 80 4 4
KT x PI 270435 4306 90 0 0
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1: Early Pink 2: Kyoryoku Toko
Table 2:The number of F1 ovules per fruit which germinated
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L. peruvianum (male)
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Cultivar (female) PI 128644 PI 128652 PI 270435 Average
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EP 2.26 (19) 1.12 (25) 1.04 (26) 1.47
KT 0.31 (39) 0.13 (31) 0.0 (26) 0.15
SI1 0.04 (26) 0.10 (30) 0.07 (41) 0.07
GB2 0.0 (22) 0.0 (12) 0.0 (12) 0.0
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Average 0.65 0.34 0.28
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Numerals in parentheses are the number of fruit
1: Sekaiichi, 2: Giban No. 1
Table 3: Classification of embryos in the F1 ovules that appear to be capable
of germination.
______________________________________________________________ Type No. of embryos Description ______________________________________________________________ A 1 (4.3) Incomplete cotyledons were formed B 5 (21.7) Cotyledonary primordia were recognized C 9 (39.2) Rod-shaped embryos with twist in the middle D 8 (34.8) Rod-shaped embryos ______________________________________________________________ Numerals in parentheses show percentage.