Three Novel Alleles and Their Functional Markers for Breeding Resistance to Powdery Mildew () in Pea.

Powdery mildew caused by DC is a global notorious disease on peas. Deploying resistance pea cultivars is the most efficient and environmentally friendly method for disease control. This study focuses on revealing the resistance genes in three pea germplasms and developing their functional markers for resistance breeding. The identification of resistance genes involved genetic mapping and the sequencing of the pea mildew resistance locus O homolog gene. To confirm the heredity of three resistant germplasms, they were crossed with susceptible cultivars to generate F, F, and F populations. The F generation exhibited susceptibility to , whereas the segregation patterns in subsequent generations adhered to the 3:1 (susceptible: resistant) and 1:2:1 (susceptible homozygotes: heterozygotes: resistant homozygotes) ratios, indicating that powdery mildew resistance was governed by a single recessive gene in each germplasm. Analysis of -linked markers and genetic mapping suggested that the resistance genes could be alleles in these germplasms. The multiple clone sequencing results of the three homologous genes showed they were novel alleles, named -15, -16, and -17. The -15 and -16 were caused by 1-bp deletion at position 335 (A) and 429 (T) in exon 3, respectively, whereas -17 was caused by a 1-bp insertion at position 248 in exon 3, causing a frame-shift mutation and premature termination of protein translation. Their respective functional markers, kompetitive allele-specific PCR (KASP)--15, KASP--16, and KASP--17, were successfully developed and validated in respective mapping populations and pea germplasms. These results provide valuable tools for pea breeding resistance to . .