Cytological investigation on microsporogenesis of cytoplasmic male sterility in radish (Raphanus sativus L.)

The cytology of the microsporogenesis and development of anther wall of cytoplasmic male sterile (CMS) lines A 2, A 4 and its maintainer lines B 2, B 4 was studied. The results revealed that the tapetal cells of the male sterile line A 2 developed abnormally at tetrad stage, and they became vacuolated and numerous small vacuoles are present; furthermore, the small vacuoles fused into large ones. Exine of microspore was light stained, and cell wall was destructed. Finally with degeneration of the tapetal cells, the pollen aborted. The tapetal cells of CMS line A 4 enlarged abnormally at meiotic phase, pressing microsporocyte seriously. Lately, light-staining exine of microspore could not be observed, and tapetal cells fused to form big lump invading the loculi, and finally leading to pollen grain abortion.