A sequence-amplified characterized region marker for a single, dominant gene in melon PI 134198 that confers resistance to a unique race of Podosphaera xanthii in China

Abstract

Melon production in China is threatened by cucurbit powdery mildew incited by Podosphaera xanthii, which can cause severe yield losses. Disease reactions of 10 melon P. xanthii race differentials indicated the presence of a unique race of P. xanthii, denoted pxCh1, in the Shanghai area. Resistance to P. xanthii race pxCh1 in melon PI 134198, which originated from India, was controlled by a single, dominant gene, designated Pm-8, in a cross with susceptible melon inbred S717. A search for a molecular marker linked to Pm-8 was initiated using the same cross. Bulk segregant analysis of their F2 progeny revealed one sequence-related amplified polymorphism (SRAP) marker of 148 bp linked to Pm-8, at 3.9 cM. The SRAP segment was recovered, cloned, and sequenced and converted into a sequence-amplified characterized region marker for marker-assisted selection of Pm-8 in breeding programs to develop melon cultivars resistant to P. xanthii race pxCh1.