Genotyping cherry cultivars assigned to incompatibility groups, by analysing stylar ribonucleases

Seventy cultivars of Prunus avium that had been assigned to incompatibility groups or to the O group of universal donors, primarily by the John Innes Institute, were analysed for stylar ribonucleases to check or determine their incompatibility, S, alleles. Three 'new' bands were detected and ascribed to new alleles S-12 to SI.. For most of the groups that had previously been genotyped most of the cultivars had the genotypes expected, although various exceptions were found. In group VIII none of the cultivars tested had the correct genotype of S2S5 but this genotype occurred in 'Malling Black Eagle'. For the three groups not previously genotyped we assigned genotypes: group X, S6S9; group XI, S2S7; and group XII S6S13. We confirmed group XIV, which had been rejected by Canadian work. Group O comprised a range of genotypes. In collating these results and those of our previous ribonuclease studies we propose five new groups: group XV, S5S6; group XVI, S3S9; group XVII, S4S6; group XVIII, S1S9; and group XIX, S3S13. Several predictions were confirmed by test crossing; thus the three members of the proposed group XV, 'Colney', 'Erianne' and 'Zweitfruhe', were cross-incompatible, as were the two members of proposed group XVIII, 'Norbury's Early Black' and 'Smoky Dun.'