COMPARATIVE-ANALYSIS OF FEMALE AND MALE MEIOSIS IN 3 MEIOTIC MUTANTS OF TOMATO

Female meiosis was analysed in squash preparations of ovules from thre e meiotic mutants and wild-type plants of tomato. In the completely as ynaptic mutant as6, chromosome pairing and chiasma formation were virt ually absent in both sexes. In the partially asynaptic mutant asb, wit h intermediate levels of chromosome pairing at pachytene, there were a higher number of chiasmate chromosome arms in female meiosis than in male meiosis, whereas in the desynaptic mutant as5 there were normal l evels of chromosome pairing at pachytene and a similar reduction in ch iasma frequency in the two sexes. In wildtype tomato, we found slightl y higher numbers of chiasmate chromosome arms in female meiosis than i n male meiosis. We propose that the higher female chiasma frequencies in mutant asb and wild-type tomato result from a longer duration of fe male meiotic prophase. This would allow chromosomes more time to pair and recombine. It is possible that a longer duration of prophase I doe s not affect mutants as5 and as6, either because the meiotic defect ac ts before the pairing process begins (in as6) or because it acts at a later stage and involves chiasma maintenance (in as5).