A major locus for resistance to Botryosphaeria dothidea in Prunus

Species in the fungal family Botryosphaeriaceae are significant pathogens of peach. The climatic conditions in the Southeastern USA are conducive to the development of peach fungal gummosis (PFG) with an estimated yield reduction of up to 40% in severe cases. Genotypes with resistance to this PFG were identified in interspecific crosses and segregating backcross populations generated using Kansu peach (Prunus kansuensis Rehder), almond [Prunus dulcis (Mill.) D.A. Webb], and peach [Prunus persica (L.) Batsch]. Hybrids were evaluated for four consecutive years in field conditions. Data generated was validated in different environments using clonal replicates of the hybrids. The F-1 and BC1F1 segregation population data suggest a dominant allele for PFG resistance originating from almond. Segregation and mapping analysis located the PFG resistance locus on a chimeric linkage groups 6-8 near the leaf color locus. The molecular markers identified will facilitate marker-assisted selection (MAS) and introgression of this resistance trait into commercial peach germplasm.