Discriminating styles (DS) and pollen-mediated pseudo-self-compatibility (PMPSC) in Nemesia strumosa benth. : Part 2: origin of PMPSC and nature of the DS-PMPSC interaction.

Nemesia strumosa pollinators which produced significantly more seeds than other pollinators following incompatible pollinations onto discriminating styles (DS) had pollen-mediated pseudo-self-compatibility (PMPSC). Level of PMPSC was not affected by relatedness between the pollen and style. When a plant expressed PMPSC, either it or its ancestors had intermediate or high pseudo-self-compatibility (PSC) levels, though these conditions did not guarantee PMPSC. Except within families, self PSC level was not related to PMPSC level. Generally, members of the same family showed similar patterns of DS and PMPSC response. When differences occurred, they were related to the level of discriminating sensitivity and self PSC respectively. Incompatible diallel crosses among related and unrelated plants revealed similar patterns of seed set, indicating that the interaction between DS and PMPSC pollinators was of a general nature. Both PMPSC genes and DS genes are PSC genes, though not the same genes. The products of PMPSC genes and DS genes interact to determine self or incompatible-cross seed set level.