Plant Genome III Conference Plant Genome III Conference
We have constructed a genetic linkage map of peach [Prunus persica (L.) Batsch] consisting of RFLP, RAPD and morphological markers, based on 71 F2 individuals derived from the self- fertilization of four Fl individuals of a cross between 'New Jersey Pillar' and KV 77119. This progeny, designated as the West Virginia (WV) family, segregates for genes controlling canopy shape, fruit flesh color, and flower petal color, size and number. The segregation of 65 markers comprised of 46 RFLP loci, 12 RAPD loci and 7 morphological loci was analyzed. The current genetic map for the WV family contains 47 markers assigned to eight linkage groups covering 332 centimorgans (cM) of the peach nuclear genome. The average distance between two adjacent markers is 8 cM. We are transferring these markers to crosses segregating for fruit quality traits ('Bailey' x 'Suncrest', 'Boone County'x'Suncrest'). Fifteen out of 28 (54%) genomic clones that produced 46 RFLP loci in the existing West Virginia peach map detect polymorphism in each of the two fruit quality mapping progenies. Significant shared polymorphism is also evident in two additional unrelated families ('Jalhousia' x 'Summergrand, and 'Marsun' x 'White Glory'). This supports our hypothesis that RFLP markers in general, and those we've identified in particular, will serve as anchor loci in maps produced with new peach crosses. In contrast, only one RAPD marker out of 12 (18%) was also polymorphic in the new progenies, however, these markers have other important advantages that make them very useful in map construction and gene tagging. Currently, we are screening cDNA libraries and genes of known function to identify more polymorphism in our mapping populations. At this point, in the, 'Bailey' x 'Suncrest' family, 13 cDNA clones have been screened, identifying 4 (30%) polymorphic loci. In the other family ('Boone County' x 'Suncrest'), 8 other cDNA clones have been screened, but so far no polymorphism has been detected.