An isoenzyme marker linked to the incompatibility locus in cherry

Analysis of two cherry progenies from semi-compatible crosses for the esterase enzyme system showed extremely distorted segregation ratios for Est-5. Analysis of two progenies from compatible crosses for esterase and for stylar ribonuclease proved that Est-5 is linked with the incompatibility locus S. The recombination fraction is 4%. About a fifth of some 50 cultivars or selections genotyped for Est-5 were heterozygous. The various heterozygotes could provide ’testers’ for the presence in cultivars of unknown genotype of 8 of the 11 known S alleles. A seedling suitable for testing S ₉ has been identified and crosses have been made to raise testers for S ₁₀ and S ₁₁ . Isoenzyme analysis of the four progenies for glutamate oxaloacetate transaminase, and of one of them for isocitrate dehydrogenase, showed no evidence for the linkage of Got-1 or Idh-2 with S, contrary to a previous report. Estimation of linkage with S in semi-compatible crosses is discussed. Received: 16 April 1999 / Accepted: 22 June 1999