A COMPARATIVE LIGHT‐ AND ELECTRON‐MICROSCOPIC STUDY OF MICROSPOROGENESIS IN MALE STERILE (MS,) AND MALE FERTILE SOYBEANS (GLYCINE MAX (L.) MERR.)

Abstract

A comparative study of microsporogenesis in fertile and in male sterile ( ms 1 ) 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 ms 1 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 ( ms 1 ) microsporogenesis has shown that nuclear and cytoplasmic events must occur at precise times for the successful development of 1 n pollen grains from 2 n sporogenous cells. Any disruption during this process leads to sterility.