Shikimate Dehydrogenase Allozymes: Inheritance and Close Linkage to Fruit Color in the Diploid Strawberry

Abstract

The inheritance of shikimate dehydrogenase (SDH) allozymes, and their linkage relationships with phosphoglucoisomerase (PGI-2) and a locus governing red versus yellow fruit color were studied in the diploid (2n = 2x = 14) strawberry. SDH behaved as a monomeric enzyme with alternate, codominant alleles at a single locus. In the F2 generation of reciprocal crosses between Fragaria vesca Alpine cultivars Baron Solemacher (red fruit) and Yellow Wonder (yellow fruit), SDH segregated in a 1:2:1 ratio, and fruit color segregated 3 red/1 yellow. The SDH and fruit color segregations were highly correlated, with a recombination frequency of 1.1%. Diploid USDA accession FRA 364 was heterozygous with respect to both SDH and PGI-2. Both isozymes segregated 1:1, and assorted independently of each other in the F1 generation of crosses between FRA 364 (as male) and the two Alpine cultivars. The close (1.1 cM) linkage detected between the SDH and fruit color loci constitutes the first report of quantified genetic linkage in the strawberry