Desynapsis and Sterility in Solanum wendlandii Hook

The cause of sterility in Solanum wendlandii Hook. (2n=24) which is reproductively known to be a fertile plant in U.S.A. is revealed here by the desynaptic behaviour of chromosomes. The cytological observations reveal that only a few PMC's show normal behaviour of chromosomes. In most of the other cells, only a few bivalents are formed associated with varying number of univalents which range from 4 to 20 in a cell. Occasionally complete desynapsis has also been observed with 24 univalents. In addition, their behaviour at anaphase I and II is highly irregular. The unequal disjunction is a frequent phenomenon with a distribution of 2+22, 4+20, 6+18, 9+15, 10+14 etc., at the poles. The tetrad formation is also irregular. More than 60% of the pollen grains look empty. Thus there is a high degree of pollen sterility due to desynaptic behaviour of chromosomes, which may be due to partly genetical and partly environmental conditions.