THE ASSOCIATION BETWEEN POLLEN SIZE AND RENNER COMPLEX IN OENOTHERA-VILLARICAE AND OENOTHERA-PICENSIS SSP PICENSIS AND THEIR HYBRIDS - EVIDENCE FOR PREANTHESIS POLLEN COMPETITION

In both Oenothera villaricae Dietrich and O. picensis ssp. picensis, c hromosomes are transmitted as two Renner complexes. Reciprocal combina tions of the Renner complexes produce eight different F-1 hybrids, but only seven are viable. Each species, and each F-1 hybrid, produces th ree sizes of pollen, approximately 50% small sterile grains, 15% mediu m-sized viable grains and 35% large viable grains. Medium- and large-s ized grains were separated manually and subjected to random amplified polymorphic DNAs (RAPDs) analysis. A pattern of RAPD amplifications wa s obtained which indicates that, for each species and F-1 hybrid, one specific Renner complex characterizes the medium- and another the larg e-sized viable pollen. The results indicate that pollen size is determ ined in part by the pollen genotype and in part by the genotype of the other pollen grains developing within the same anther.