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 F 2 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.