TARGETED MAPPING AND LINKAGE ANALYSIS OF MORPHOLOGICAL ISOZYME, AND RAPD MARKERS IN PEACH

Nine different F2 families of peach [Prunus persica (L.) Batsch] were analyzed for linkage relationships between 14 morphological and two is ozyme loci. Linkage was detected between weeping (We) and white flower (W), 33 cM; double flower (Dl) and pillar (Br), 10 cM; and flesh colo r (Y) and malate dehydrogenase (Mdh1), 26 cM. A leaf variant phenotypi cally distinct from the previously reported wavy-leaf(Wa) mutant in pe ach was found in progeny of 'Davie II'. The new willow-leaf character (designated Wa2) was closely linked (0.4 cM) to a new dwarf phenotype (designated Dw3). Two families derived from the pollen-fertile cultiva r 'White Glory' segregated for pollen sterility, but segregation did n ot follow a 3:1 ratio. Evidence is presented suggesting that 'White Gl ory' possesses a pollen-sterility gene (designated Ps2) that is non-al lelic to the previously reported pollen-sterility gene (Ps) in peach. Ps2 was linked to both weeping (We-Ps2, 15.5 cM) and white flower (Ps2 -W, 25.3. cM). A genomic map of peach containing 83 RAPD, one isozyme, and four morphological markers was generated using an F2 family obtai ned by selfing an NC174RL x 'Pillar' F1. A total of 83 RAPD markers we re assigned to 15 linkage groups. Various RAPD markers were linked to morphological traits. Bulked segregant analysis was used to identify R APD markers flanking the red-leaf (Gr) and Mdh1 loci in the NC174RL x 'Pillar' and 'Marsun' x 'White Glory' F2 families, respectively. Three markers flanking Mdh1 and ten markers flanking Gr were identified. Th e combination of RAPD markers and bulked segregant analysis provides a n efficient method of identifying markers flanking traits of interest. Markers linked to traits that can only be scored late in development are potentially useful for marker-aided selection in trees. Alternativ es for obtaining additional map order information for repulsion-phase markers in large F2 populations are proposed.