In genic male sterility (GMS) the breakdown of microsporogenesis is mediated by dominant genes as well as by multiple recessive genes (Gottschalk and Kaul 1974, Albertsen and Palmer 1979). When compared to cytoplasmic male sterile plants (Laser and Lersten 1972, Hegde and Isaacs 1992), only a few reports are available on the cytology and microsporogenesis of genic male sterile plants. Cheng et al. (1979) found that vacuolation and cytoplasmic disintegration of tapetal cells precede the pollen abortion in GMS Zea mays. Albertsen and Palmer (1979) in Glycine max, and Takahashi (1986) in Houttuynia cordata attributed pollen abortion to failure of cytokinesis and formation of coenocytic microspores. Failure of callose breakdown resulting in the non-separation of tetrads was thought to be responsible for sterility in the GMS Cajanus cajan (Reddy et al. 1978). In contrast, Dundas et al. (1981) reported early degeneration of the tapetum as a cause for sterility in B-15-B version GMS Cajanus cajan. Sawhney and Bhadula (1988) suggested that low esterase activity caused the delay in the tapetal degeneration and failure of exine formation in male sterile stamenless-2 mutant of Lycopersicon esculentum. In this plant, effect of temperature, mediated through endogenous IAA and Polyamines, was also implicated as responsible for male sterility (Rastogi and Sawhney 1990a, b, Singh et al. 1992). Shukla and Sawhney (1992) suggested the possible involvement of cytokinins in the expression of sterility in GMS Brassica napus. In male sterile mutant of Oenothera absence of ektexine sporopollenin precursors was considered responsible for male sterility (de Halac et al. 1990). Association of tapetal hypertrophy with sterility was observed in some mutants of barley (Singh and Kaul 1990, 1991). The diversity in the cytological and morphological characters in different sterile lines of Cajanus cajan (Reddy et al. 1978, Dundas et al. 1981) suggests that the sterility is conditioned by different genes which have different physiological effects. Therefore, there is still a scope to investigate types of sterility expression in other male sterile sources of GMS Cajanus cajan to test the hypotheses already proposed. The present study compares microsporogenesis in the fertile line Cajanus cajan with its GMS (ms Prabhat) counterpart, at the light microscope level. Materials and methods Cajanus cajan (L.) Millsp. (ms Prabhat) seeds were obtained from International Crops Research Institute for Semi-Arid Tropics (ICRISAT), Hyderabad, India. Plants were raised in the Karnatak University Botanical garden. The male-sterile plants were identified by their pale yellow shrivelled anthers. Flowers from fertile and sterile plants were fixed for two hours in * To whom correspondence .

No abstract