Inheritance of isozyme production and sexual reproduction in Phytophthora infestans

Analysis of the isozyme patterns of glucosephosphate isomerase and peptidase from selfed progeny of isolates of Phytophthora infestans showed that some gave only a single slow or fast band, whereas others gave three bands, i.e., a slow, a fast, and an intermediate band. These results are consistent with the hypothesis that each locus is controlled by a single codominant gene. The single-banded pattern, either slow or fast, is due to homozygosity of one or the other allele, while the three-banded pattern is due to heterozygosity. The results also show that the genes for glucosephosphate isomerase and peptidase are not linked. Progeny from direct pairings between isolates with different homozygous genotypes for isozyme patterns consisted of selfs of both parents and hybrids, self of one parent and hybrids, and hybrids only. Key words: Phytophthora infestans, genetics, isozyme pattern.