Ovaries with different heterozygosity levels of their genotypes have equal chances to reach maturity on a buckwheat plant: Is it the main condition for the start of the evolution toward selfing?

Background. Inbreeding depression (ID) usually reduces the competitive ability of an individual compared to one of outbred origin. Such competition could be especially clear between different ovaries developing on the same plant. It can be assumed that ovaries with higher level of heterozygosity will have an advantage in competition for resources.

Material and methods. Homostylous buckwheat lines (Fagopyrum esculentum Moench with approx. 3% of closely related selfer F. homotropicum Ohnishi germplasm) of different inbred generations (I₁ – I₆ ) were grown adjacent to the heterostylous cv. ‘Molva’, and the share of seeds resulting from cross-pollination was assessed for each variant using the recessive marker det (genotypes of the seeds were visualized according to phenotypes of the resulting plants).

Results and conclusions. The proportions of seeds originated from cross-pollination were similar across the inbreeding generations, with small stochastic variations. Thus, the ovaries resulting from both selfand cross-pollination have equal chances to reach maturity on the same plant. It looks like a fundamental condition for the start of the evolution toward self-pollination. The levels of ID at other developmental stages, apparently, are less crucial for the possibility of such evolution. For example, the ID in the analyzed material was strong (> 0.5 for both vegetative development and seed productivity). It highly likely reflects the level of ID of the common ancestor of F. esculentum and F. homotropicum. However, the strong ID did not make impossible the speciation of the self-pollinator F. homotropicum.

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