DISCREPANCY BETWEEN SPINDLE ANOMALIES AND 2N POLLEN PRODUCTION IN SOLANUM INTERSPECIFIC HYBRIDS

The cytological basis of 2n pollen production was studied in a diploid Solanum progeny coming from a cross between a S. tuberosum-S. chacoen se hybrid which does not produce 2n pollen (T710) and a S. phureja-S. tuberosum hybrid (W5295.7) which does. Both parental clones showed ano malous orientation of spindles at Metaphase II of microsporogenesis, b ut only clone W5295.7 produced dyads. All plants of the progeny T710 x W5295.7 showed anomalous spindles at Metaphase II, but only 60% of th em produced 2n pollen, thus evidencing a discrepancy between spindle a nomalies and dyad/2n pollen production. This may suggest that both par allel and fused spindles are a necessary but insufficient condition fo r 2n pollen production, and that some other mechanisms expected to be more highly correlated with them may be involved in 2n pollen producti on in this population.