Molecular Characterizations of the er1 Alleles Conferring Resistance to Erysiphe pisi in Three Chinese Pea ( Pisum sativum L.) Landraces

Powdery mildew caused by DC. is a major disease affecting pea worldwide. This study aimed to confirm the resistance genes contained in three powdery mildew-resistant Chinese pea landraces (Suoshadabaiwan, Dabaiwandou, and Guiwan 1) and to develop the functional markers of the novel resistance genes. The resistance genes were identified by genetic mapping and gene sequence identification. To confirm the inheritance of powdery mildew resistance in the three Landraces, the susceptible cultivars Bawan 6, Longwan 1, and Chengwan 8 were crossed with Suoshadabaiwan, Dabaiwandou, and Guiwan 1 to produce F , F , and F populations, respectively. All F plants were susceptible to , and phenotypic segregation patterns in all the F and F populations fit the 3:1 (susceptible: resistant) and 1:2:1 (susceptible homozygotes: heterozygotes: resistant homozygotes) ratios, respectively, indicating powdery mildew resistance in the three Landraces were controlled by a single recessive gene, respectively. The analysis of -linked markers and genetic mapping in the F populations suggested that the recessive resistance genes in three landraces could be alleles. The cDNA sequences of 10 homologous cDNA clones from the contrasting parents were obtained. A known allele, -4, was identified in Suoshadabaiwan. Two novel alleles were identified in Dabaiwandou and Guiwan 1, which were designated as -13 and -14, respectively. Both novel alleles were characterized with a 1-bp deletion (T) in positions 32 (exon 1) and 277 (exon 3), respectively, which caused a frame-shift mutation to result in premature termination of translation of protein. The co-dominant functional markers specific for -13 and -14, KASPar- -13, and KASPar- -14 were developed and effectively validated in populations and pea germplasms. Here, two novel alleles were characterized and their functional markers were validated. These results provide powerful tools for marker-assisted selection in pea breeding.