Rosbreed: Enabling Marker-assisted Breeding for Brown Rot (Monilinia spp.) Resistance in Peach

Brown rot, caused by Monilinia spp., is one of the most important diseases of stone fruits. The fungus mainly infects blossoms and fruits, and can result in significant yield losses. Estimated yearly cost to the U.S. stakeholders for chemical protection against bloom blight and pre- and post-harvest fruit decay is $170M. Although some degree of resistance has been found in the Brazilian cultivar Bolinha and some cultivars and advanced selections developed in the UC Davis and USDA breeding programs, genetic resistance to brown rot in peaches is still lacking. In commercial peach production, the two phases of the disease (blossom and fruit infection) can only be controlled with routine fungicide applications, which cause both environment and fungicide resistance concerns. The RosBREED project, is combining disease resistance with horticultural quality by evaluating sources of brown rot resistance/high tolerance in peach germplasm and enabling pyramiding and combining resistant alleles in fresh market and processing peach. Phenotyping protocol, developed at UC Davis, includes controlled laboratory inoculation of unwounded and wounded peach fruit on a panel of peach breeding germplasm. The next generation of peach cultivars with superior horticultural quality and disease resistance/tolerance will reduce the human health risks and environmental costs associated with pesticides load in the agro-ecosystem. Consumers will benefit from greater access to a more stable supply of nutritious fruit with superior eating qualities that will translate into increased per capita consumption and improved human health and well-being. Preliminary results from the first year of this study will be presented and discussed in detail.