Exotic genes for solving emerging peach production challenges: mechanical harvest

Peach is entering a period of transformation, driven by changes in climate, production methods and market trends but where future breeding progress is severely limited by its very narrow genetic base. Peach rootstocks have a long history of utilizing interspecies hybridization to successfully incorporate needed traits for disease, pest and environmental stress resistance. Interspecies hybridizations resulting in commercially successful rootstocks have been made between cultivated peach and its wild peach relatives, as well as the more distantly related cultivated almond and its numerous and ecologically diverse wild relatives. Efforts to further introgress such exotic interspecies hybrids for peach cultivar improvement have successfully transferred not only tolerance to diseases, pest and environmental stresses but also improved fruit and tree quality. In a program to develop commercial quality processing peaches amenable to mechanical harvest, traits for fruit brown-rot resistance and capability for single-pass harvest as well as tree architectures facilitating mechanical harvesting have been successfully identified and transferred. Heritability of most traits derived from exotic germplasm, however, remains poorly studied, though early research suggests genomic and epigenetic modifications may sometimes be involved in addition to more traditionally studied genetic changes.