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Article|01 Nov 2020|OPEN
Fine mapping and identification of candidate genes for the peach powdery mildew resistance gene Vr3
Neus Marimon1,2,3, Jordi Luque3, Pere Arús1,2 & Iban Eduardo1,2,
1Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB, 08193 Bellaterra, Barcelona, Spain
2IRTA (Institut de Recerca i Tecnologia Agroalimentàries), Barcelona, Spain
3Plant Pathology, IRTA Cabrils, Carretera de Cabrils km 2, 08348 Cabrils, Spain

Horticulture Research 7,
Article number: 175 (2020)
doi: 10.1038/hortres.2020.175
Views: 466

Received: 23 May 2020
Revised: 18 Aug 2020
Accepted: 30 Aug 2020
Published online: 01 Nov 2020

Abstract

Powdery mildew is one of the major diseases of peach (Prunus persica), caused by the ascomycete Podosphaera pannosa. Currently, it is controlled through calendar-based fungicide treatments starting at petal fall, but an alternative is to develop resistant peach varieties. Previous studies mapped a resistance gene (Vr3) in interspecific populations between almond (‘Texas’) and peach (‘Earlygold’). To obtain molecular markers highly linked to Vr3 and to reduce the number of candidate genes, we fine-mapped Vr3 to a genomic region of 270 kb with 27 annotated genes. To find evidence supporting one of these positional candidate genes as being responsible of Vr3, we analyzed the polymorphisms of the resequences of both parents and used near-isogenic lines (NILs) for expression analysis of the positional candidate genes in symptomatic or asymptomatic leaves. Genes differentially expressed between resistant and susceptible individuals were annotated as a Disease Resistance Protein RGA2 (Prupe2G111700) or an Eceriferum 1 protein involved in epicuticular wax biosynthesis (Prupe2G112800). Only Prupe2G111700 contained a variant predicted to have a disruptive effect on the encoded protein, and was overexpressed in both heterozygous and homozygous individuals containing the Vr3 almond allele, compared with susceptible individuals. This information was also useful to identify and validate molecular markers tightly linked and flanking Vr3. In addition, the NILs used in this work will facilitate the introgression of this gene into peach elite materials, alone or pyramided with other known resistance genes such as peach powdery mildew resistance gene Vr2