First genomic insights into the introgression of almond PPV-Marcus resistance into peach
TL;DR
This study provides the first evidence of genomic regions associated with PPV-Marcus response in almond × peach populations and provides an initial basis to support the introgression of almond-derived resistance into peach breeding material.
Abstract
Aim Sharka, caused by Plum pox virus (PPV), is one of the most damaging viral diseases of stone fruit crops, with peach among the most susceptible cultivated Prunus species. Almond is a promising source of resistance, but its genetic architecture and expression in a peach genetic background remain largely unknown. This study aimed to construct parental genetic linkage maps and identify genomic regions associated with PPV response in almond × peach interspecific populations. Methods Progenies derived from the almond cultivars ‘Del Cid’, ‘Garrigues’, and ‘Mono’ were evaluated by RT-PCR after graft inoculation with the PPV-Marcus (PPV-M) strain over consecutive infection cycles. Phenotypic data were summarized for each genotype using best linear unbiased estimates (BLUEs). High-density SNP almond and peach arrays were used to construct parental maps for ‘Garrigues’ and ‘Mono’ and perform quantitative trait locus (QTL) analysis. Results Phenotypic variation was observed among and within families. ‘Del Cid’-derived progenies showed the greatest resistance, ‘Garrigues’-derived progenies displayed intermediate responses, and ‘Mono’-derived progenies showed greater susceptibility and variability. The parental maps covered 546.69 cM in ‘Mono’ and 521.72 cM in ‘Garrigues’, with average intervals of 0.61 and 1.26 cM per unique marker position, respectively, and showed strong collinearity with the reference genome. QTL associated with PPV-M response were detected on linkage groups (LG) 1 and 6 in ‘Garrigues’ and LG2 in ‘Mono’. The main QTL in ‘Garrigues’ peaked near 22.39 Mb on LG1, whereas the ‘Mono’ QTL was located at 22.27–22.62 Mb on LG2; a weaker QTL was detected near 25.38 Mb on LG6 in ‘Garrigues’. The results support a quantitative and genetic-background-dependent architecture of PPV resistance. Conclusion This study provides the first evidence of genomic regions associated with PPV-Marcus response in almond × peach populations. The detected QTLs provide an initial basis to support the introgression of almond-derived resistance into peach breeding material.