An isoenzyme marker linked to the incompatibility locus in cherry

Analysis of two cherry progenies from semicompatible crosses for the estera se enzyme system showed extremely distorted segregation ratios for Est-5. A nalysis of two progenies from compatible crosses for esterase and for styla r 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 s elections genotyped for Est-5 were heterozygous. The various heterozygotes could provide 'testers' for the presence in cultivars of unknown genotype o f 8 of the Il 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 transam inase, 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. Es timation of linkage with S in semi-compatible crosses is discussed.