INFLUENCE OF CYTOPLASMIC-NUCLEAR MALE-STERILITY SYSTEMS ON MICROSPOROGENESIS IN PEARL-MILLET (PENNISETUM-GLAUCUM (L.) R. BR.)

Influence of a range of cytoplasms on microsporogenesis and anther dev elopment in pearl millet was studied using six isonuclear A-lines havi ng five cytoplasms (A(1), A(2), A(3), A(4) and A(v)) and the nuclear g enome of 81B. 81B was used as a male-fertile control. Microsporogenesi s and anther development were normal in 81B. However, pollen mother ce ll (PMC)/microspore/pollen degeneration in the six A-lines occurred at different stages of anther development. Each cytoplasm had its unique influence on microsporogenesis and anther development as evidenced by different developmental paths followed by them leading to pollen abor tion. The cause of pollen abortion differed from line to line, from fl oret to floret within a spikelet, from anther to anther within a flore t, and in some cases even from locule to locule within an anther. Even ts that led to male sterility included anomalies in tapetum and callos e behaviour, persistence of tapetum, endothecium thickness, and other unknown causes. The present study also indicated that anther/pollen de velopment was more irregular in Pb 406A(3). In 81A(4) and 81A(1) > 95% of anther locules followed a definite developmental path to pollen ab ortion. In the other A-lines many developmental paths were observed wi thin the line and pollen degeneration occurred at various stages. This could be one of the reasons for greater instability of male sterility in the A(2) and A(3) systems and greater stability of male sterility in the A(1) and A(4) systems.