Segregation and linkage of allozymes in megagametophyte tissues of pinus thunbergii parl

As a first step in the study of genetics of Pinus thunbergii Parl., the inheritance and the linkage of the detected polymorphisms were elucidated. Megagametophyte tissues of individual seeds from a single clone were analysed by starch gel electrophoresis. Seven enzyme systems studied comprised a minimum of 17 isozyme loci. Among them, 11 were polymophic. Segregation of isozymes in megagametophytes of heterozygous maternal clones indicated no significant departure from the expected 1 : 1 ratio in each locus. Significant linkage, as attested by the 95% confidence interval, was recognized in six pairwise combinations. The pairs of the gene loci ME-B/LAP-A and ADH-B/MNR-C were closely linked with estimated mean recombination values of 0.153 and 0.175, respectively. The remaining tested pairs (ADH-B/ LAP-B, ME-B/MDH-C, MNR-B/MDH-C, and MNR-A/MNR-B) appeared to be weakly linked. The gene loci MNR-C, ADH-B, and LAP-B could be linearly arranged in one linkage group, while the loci LAP-A, ME-B, MDH-C, MNR-A, and MNR-B seemed to belong to the other linkage group. Considerable variation with respect to the estimated recombination frequencies was observed for the same pair of loci among some clones. A comparsion with other conifer species showed that the gene orders and distances were relatively well conserved among conifer species.