VARIABLE DEVELOPMENT IN ANTHERS OF PARTIALLY MALE-STERILE SOYBEANS
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Results are reported of a cytological investigation ot floral bud development in male-fertile, Msp ---, and partially male-sterile, msp msp, soybean (Glycine max L. Merr.) plants. Our objective was to determine the cytological causes of partial male sterility. Paraffin-embedded specimens and squash preparations from field- and greenhouse-grown plants were analyzed. Development of msp anthers was highly variable and included numerous cytological abnormalities. Arrest of development and subsequent degeneration of sporogenous tissues occurred at all stages of anther development from the sporogenous cell stage to the pollen stages, but the onset of abnormalities was most frequent near pachytene and at the tetrad and free-microspore stages. Cytomixis and syncyte formation occurred in some microsporangia. Meiocytes in anthers of the upper whorl tended to attain more advanced stages of development than did those of the lower whorl. Degenerating sporogenous tissue usually was associated with degenerating tapetal tissue, whereas degenerating tapetal tissue was associated with healthy sporogenous tissue in some microsporangia. This relationship between sporogenous and tapetal tissue suggests either that abnormalities in the tapetum led to degeneration of sporogenous tissue or that tapetal cells were prone to manifest more quickly an abnormality common to a microsporangium. 1982, American Genetic Association.