Restoration of pseudo-self-compatibility (PSC) in derivatives of a high-PSC × no-PSC cross in Nemesia strumosa Benth
SummaryMean PSC increased following each generation of recurrent selection in F1, F2 and F3Nemesia strumosa families derived from a cross of a 100% PSC plant to an unrelated 0% PSC plant. The first 100% PSC individuals occurred in the F4. Populations derived through sib pollination tended to have higher PSC means than lines derived through self pollination. One F3 family showed a three-fold higher PSC level when pollinated in the green-house than when pollinated in the growth chamber, while another F3 family similarly pollinated showed no change in PSC.
Discriminating styles (DS) and pollen-mediated pseudo-self-compatibility (PMPSC) in Nemesia strumosa Benth.
SummaryNemesia 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.
New Self-incompatibility Alleles produced through Inbreeding
By drawing a parallel with microbial systems it is possible to envisage a scheme of intracistronic recombinations which could give rise to new self-incompatibility alleles.