Reciprocal compatibility within the genus Pisum L. as studied in F₁ hybrids: 4. Crosses within P. sativum L. subsp. elatius (Bieb.) Aschers. et Graebn.

Five accessions representing divergent lineages of wild peas (Pisum sativum subsp. elatius) were crossed with each other in both directions and also artificially pollinated with own pollen, to evaluate reproductive barriers inside Pisum sativum which may be important for pea pre-breeding. The outcome of hybrid seeds was evaluated for each combination of crosses. Reciprocal classes of F₁ hybrids were compared for pollen and seed fertility and quantitative traits including seed productivity, total biomass etc. Pollination of accession VIR320 with two accessions resulted in hybrids with drastically reduced leaves and pigmentation, resembling known cases of conflict of the nucleus and plastids. Four pairs of reciprocal F₁ hybrids showed strong differences in male and female fertility, supposedly a milder manifestation of cytonuclear conflict. Male and female fertility of hybrids correlated with each other, the former appearing more convenient for evaluating genetic disturbance of gametogenesis. Only two hybrid classes showed fully fertile pollen. Some of the accessions studied have been previously reported to differ in a reciprocal translocation and their hybrids were expected to have half-sterile pollen. However accession VIR320 seems to ‘bridge’ both karyological classes showing relatively high pollen fertility in some crosses with representatives of both of them, the reasons for which is discussed. Generally, strong and usually asymmetric cases of incompatibility manifested in the drop of fertility were revealed and their pattern did not correlate with phylogenetic relatedness of the accessions. Hence, wild representatives of P. sativum can hardly be subdivided into natural biological taxa below species rank and their involvement in pea pre-breeding can be complicated by unexpected crossing barriers.