GENETICS AND CYTOLOGY OF A NEW GENIC MALE-STERILE SOYBEAN [GLYCINE-MAX (L) MERR]

Genetic and cytological studies were conducted with a now male-sterile , female-fertile soybean [Glycine max (L.) Merr.] mutant. This mutant was completely male sterile and was inherited as a single-recessive ge ne. No differences in female or male gamete transmission of the recess ive allele were observed between reciprocal cross-pollinations in the F-1 or F-2 generations. This mutant was not allelic to any previously identified soybean genic male-sterile mutants: ms1, ms2, ms3, ms4, ms5 , or ms6. No linkage was detected between sterility and flower color ( W1 locus), or between sterility and pu bescence color (T1 locus). Ligh t microscopic and cytological observations of microsporogenesis in fer tile and sterile anthers were conducted. The structure of microspore m other cells (MMC) in male-sterile plants was identical to the MMCs in male-fertile plants. Enzyme extraction analyses showed that there was no callase activity in male-sterile anthers, and this suggests that st erility was caused by retention of the callose walls, which normally a re degraded around tetrads at the late tetrad stage. The tapetum from male-sterile anthers also showed abnormalities at the tetrad stage and later stages, which were expressed by an unusual formation of vacuole s, and by accumulation of densely staining material. At maturity, anth ers from sterile plants were devoid of pollen grains.