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Almond species as sources of new genes for peach improvement

Gradziel, T.M.
Acta horticulturae 2002 no.592 pp. 81-88
Monilinia fructicola, Prunus dulcis, Prunus persica, Sphaerotheca, Taphrina deformans, almonds, breeding lines, cultivars, flowers, genes, germplasm, hybrids, introgression, leaf curling, mechanical harvesting, peaches, phenotype, phenotypic variation, powdery mildew, recurrent selection, rootstocks, trees, China
A major limitation to the improvement of peach (Prunus persica) is its genetic uniformity. Almond (Prunus dulcis) is readily crossed with peach and interspecific hybrids are important rootstocks. Considerable phenotypic variability exists in the cultivated almond and wild almond-like species which are found from north Africa to China. The introgression of this germplasm to peach, often using P. dulcis as a bridge species, has led to the recovery of a range of potentially useful traits. These include modified tree shape, size, and structure, modified fruit bearing habit including spur-bearing peaches, and low bruising, long-hanging peaches which facilitate once-over and mechanical harvesting. Flower and fruit traits include the modified flowering habits of cleistogamy and pollen-pistil self-incompatibility, and firm-flesh non-melting freestone types. Field resistance has been observed for the diseases brown rot (Monilinia fructicola), powdery mildew (Sphaerotheca spp.), peach leaf curl (Taphrina deformans), and Phytopthora spp. rots. No significant breeding barriers to almond gene introgression to peach have been observed. Certain traits, such as brown rot resistance and spur-bearing habit were recovered in locally adapted peach breeding lines using recurrent selection strategies. Several traits occurred as novel variants and are not easily predicted from parent phenotypes. Preliminary observations, based on the introgression of only a very small proportion of the available germplasm, suggests a previously under recognized value of this germplasm to peach cultivar and rootstock improvement.