Inheritance of Resistance to Race 5 of Powdery Mildew Fungus Podosphaera xanthii in Melon and Development of Race 5-Specific High Resolution Melting Markers

Abstract

Powdery mildew (PM), caused by the biotrophic fungus Podosphaera xanthii, drastically reduces the yield and quality of melon (Cucumis melo L.). Knowledge on the genetic control and high throughput molecular markers linked with resistance against this disease are essential for breeding programs. The bioassay study of the F 1 and F 2 populations derived from the parents, ‘PMR 5’ ((cid:0)) and ‘SCNU1154’ ((cid:0)) revealed a monogenic dominant nature of resistance to the devastating race, race 5. Besides, we developed three SNP based high resolution melting markers, PMm-HRM-1, PMm-HRM-2, and PMm-HRM-3 based on the previously identi�ed SNPs on chromosome 12 and validated those using 10 melon lines and 137 F 2 population. Among these, the SNP of marker PMm-HRM-1 causes a missense mutation (Lysine → Glutamic acid) in the LRR region of MELO3C002393 and were able to distinguish the resistant vs susceptible genotypes from 10 diverse melon population and the segregating F 2 population with more than 90% genotyping e�ciency. Other two markers were based on intergenic SNPs and had more than 80% genotyping e�ciency F 2 population. These markers will be helpful to melon breeders to develop melon cultivars resistant to P. xanthii race 5 via marker assisted breeding programs. and 1 s at 97°C. HRM data was performed using LightCycler 96 software at 100% discrimination for delta Tm and curve shape with a 0.2 positive/negative threshold level.