Abstract:

A₃ male sterile cytoplasm in sorghum (Sorghum bicolor L. Moench) is from IS1112C. Among the seven kinds of cytoplasmic male sterility (CMS) in sorghum, the sterility in A₃ CMS is most stable, and very difficult to restore. In this study A₃ male sterile line Jingliang 5 and corresponding maintainer B₃ Jinliang 5 were used to study the process of A₃ CMS anther development and analyze the chromosomal behaviors of meiosis during microspore formation, in order to understand the basis of A₃ CMS genesis. The results showed that differing from that in A₁ and A₂ CMS, the meiosis of pollen mother cell (PMC) in A₃ Jinliang 5 was completed normally. No abnormal meiotic behaviors were observed compared to its corresponding maintainer B₃ Jinliang 5. In sporogenous cell stage, premeiotic interphase and meiosis stage, no abnormal phenomena were found. Tetrad separated normally in paraffin-embedded A₃ male sterile line anther section observation. But in pollen mature stage deformed pollens were observed and it was in this stage, i.e. about 7 days before anthesis, the normal development of microspores was affected, sucrose-starch metabolic pathway was blocked and no starch particles were deposited on intine of A₃ CMS pollens, leading to unviable pollen formation.

Key words: Sorghum, A₃ CMS, Meiosis