2019 ASHS Annual Conference

Combining disease resistance with superior fruit quality and climate resilient productivity is a new standard in peach breeding programs. As a result of the foundational knowledge and tools generated in RosBREED,breeders are no longer relying solely on phenotyping and serendipity but are in many cases equipped with the DNA based information when designing crosses and choosing offspring to advance. The Clemson University peach breeding program aims to combine brown rot (Monilinia spp.) and bacterial spot (Xanthomonas syringae pv. pruni) disease resistance in large, yellow flesh, melting, fresh market peach cultivars with improved climate resilience. This is easier said than done. Phenotypic data coupled with available DNA information on disease resistance and fruit quality is the main driver when designing crosses to maximize the proportion of offspring with favorable traits. A DNA test for fruit response to bacterial spot infection, developed in RosBREED, is routinely used to cull seedlings prior to planting in the field. Sources of resistance for brown rot are horticulturally inferior and development of DNA test(s) is hindered by polygenic inheritance of many genes with small effect. Thus, genomic prediction is being validated in choosing parental combinations and culling offspring. A roadmap to elite selections with confirmed superior horticultural quality and bacterial spot and brown rot tolerance using a combination of molecular and phenotyping approaches in Clemson University peach breeding program will be presented.