|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1997 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1996 : ¥1,500,000 (Direct Cost : ¥1,500,000)
Air-dried seeds of the purebred tomato, cv.First, were irradiated with gamma-rays for 5hr at 100,200 and 400Gy. Among the 188 lines in the second generation (M2) plants derived from 100Gy treatment, a type of male sterility was observed, whereas in 88 lines from 200Gy three types of male sterility were isolated : one group of male sterile mutants developed normal pistil and stamen with yellow anther, and the pollen degradation became evident at microsporegenesis. The second one was morphologically distinguishable by an exerted style because of a degenerating anther which became yellow-brown acropetally. Pollen degradation became evident around meiosis stage. The third one developed normal pistil with yellow anther, similar to those in type 1. However, the pistil became longer than the stamen a few days before anthesis, and drop of staminal-corn split at anthesis so that the stigma was disclosed. Pollen degradation became evident from tetrad to early microspore stages. For each type, wh
en heterozygous plants, Msms, was selfed, fertile and sterile progenies in the M2 and M3 generations segregated at a ratio of 3 : 1.
The fourth type of ms mutant which did not set fruits by self pollination despite having mature pollen normally stained with acetocarmine, was identified among the same M_2 population. The flower of msmutant was not distinguishable in size and color from that of original cv.First, and also produced morphologically matured pollens which were normally stained with acetocarmine. However, most of the pollens collected at anthesis were stained in black with iodine solution, suggesting that starch degradation was inhibited in these mature pollens. No fruit set was achieved by self pollination of ms mutant in spring season. Color distribution of pollen stained with iodene solution indicated that most of pollen was red in original and black over 70% in mutant. Segregation ratios of fertile and sterile and of normal and abnormal stainability both fitted to 3 : 1, indicating that inhibition of starch degradation and male sterility were controlled by respective single gene. It was indicated from these results that a pollen germination inhibiting gene (PGIG) is closely related with a starch degradation inhibiting gene.