THE FUNCTION OF THE INCOMPATIBILITY ALLELES IN RED CLOVER (TRIFOLIUM PRATENSE L)

Sexually localized expression of pseudo-self compatibility (PSC) in Petunia X hybrida Hort : 2. Stylar inactivation

A previously identified S-linked stylar-inactivation PSC factor (Flaschenriem and Ascher 1979b) was studied for its location relative to S. Plants exhibiting complete stylar-inactivation PSC were those with higher multigenic PSC background level than plants with only S-linked partial stylar-inactivation PSC. A pollen-mediated pseudo-self compatibility (PMPSC) adjustment factor was offered as a device to focus on stylar-inactivation PSC by removing some male origin, multigenic PSC. The stylar inactivation factor was not tightly linked to S but affected expression of only the allele to which it was linked. A three part interacting association of genetic material governing self incompatibility (SI) is proposed. The parts of S are the SI identity gene, S-specific PSC genes and, finally, PSC genes which are not S-specific in action. The complete association is termed the SI-complex.

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.

Discriminating styles (DS) and pollen-mediated pseudo-self-compatibility (PMPSC) in Nemesia strumosa Benth. : Part 1: Characteristics and inheritance of DS

Nemesia strumosa plants were discovered which had styles capable of discriminating among incompatible pollen tubes from different pollinators, allowing growth of some but not others. All but 3 of 26 families tested had at least some members with discriminating styles (DS). Presence and level of DS was independent of S genotype. Plants with pseudo-self-compatiblity (PSC) levels greater than 10% had the trait, though many plants with strong DS had PSC levels less than 10%. Self pollination of highly DS plants produced mostly DS offspring, but of differing sensitivities. Some progenies from crosses between a family of highly DS plants and unrelated, probably low DS plants segregated half DS and half non-DS, while others consisted of mostly DS or mostly non-DS. The DS phenomenon is probably caused by PSC genes.