University of Minnesota, Department of Agronomy and Plant Genetics, St. Paul, 55108
Science and Education Administration, USDA, Genetics Department, Iowa State University, Ames, 50011
Abstract:
A comparative study of microsporogenesis in fertile and in male sterile (ms1) soybean plants (Glycine max (L.) Merr.) was conducted by using various microscopic techniques. Once the developmental pattern for fertile microsporogenesis was established, it was compared with the developmental pattern in sterile plants to determine the time of microsporogenesis breakdown. Sterility of the ms1 mutant is caused by failure of cytokinesis after telophase II. The four nuclei resulting from meiosis become enclosed in a single-celled structure, termed a coenocytic microspore. These microspores develop a pollen-like wall and become engorged with lipid and starch reserves. Coenocytic microspores usually degenerate after engorgement. This study of fertile and sterile (ms1) microsporogenesis has shown that nuclear and cytoplasmic events must occur at precise times for the successful development of 1n pollen grains from 2n sporogenous cells. Any disruption during this process leads to sterility.