Genetic mapping and candidate gene analysis for melon resistance to Phytophthora capsici

Pingyong Wang,Shuimiao Liu,Guangwei Zhao,Chong Hou,Yuhua He,Jian Zhang,Xiaojun Xu,Weihu Kong,Zhihong Xu,Yongyang Xu

doi:10.1038/s41598-020-77600-2

Abstract

Phytophthora blight is one of the most serious diseases affecting melon (Cucumis melo) production. Due to the lack of highly resistant germplasms, the progress on disease-resistant research is slow. To understand the genetics of melon resistance to Phytophthora capsici, an F2 population containing 498 individuals was developed by crossing susceptible line E31 to highly resistant line ZQK9. Genetic analysis indicated that the resistance in ZQK9 was controlled by a dominant gene, tentatively named MePhyto. Through bulked-segregant analysis (BSA-Seq) and chromosome walking techniques, the MePhyto gene was mapped to a 52.44 kb interval on chromosome 12. In this region, there were eight genes and their expression patterns were validated by qRT-PCR. Among them, one wall-associated receptor kinase (WAK) gene MELO3C002430 was significantly induced in ZQK9 after P. capsici inoculation, but not in E31. Based on the non-synonymous mutation site in MELO3C002430, a cleaved amplified polymorphic sequence (CAPS) marker, CAPS2430, was developed and this maker was co-segregated with MePhyto in both F2 population and a collection of 36 melon accessions. Thus MELO3C002430 was considered as the candidate gene and CAPS2430 was a promising marker for marker-assisted selection (MAS) in breeding. These results lay a foundation for revealing the resistance mechanism of melon to P. capsici.

Highlights

Phytophthora blight is one of the most serious diseases affecting melon (Cucumis melo) production
We identified one melon inbred line, ZQK9, which was highly resistant to P. capsici[14]
At 10 dpi, all individuals of the F1 and BC1P2 populations were highly resistant to P. capsici, indicating that the resistance in ZQK9 was completely dominant

Summary

Introduction

Phytophthora blight is one of the most serious diseases affecting melon (Cucumis melo) production. MELO3C002430 was considered as the candidate gene and CAPS2430 was a promising marker for marker-assisted selection (MAS) in breeding. These results lay a foundation for revealing the resistance mechanism of melon to P. capsici. Padley et al identified a squash breeding line, # 394-1-27-12, with high resistance to P. capsici and predicted that its resistance was conferred by three dominant genes[12]. We identified one melon inbred line, ZQK9, which was highly resistant to P. capsici[14]. Candidate gene was predicted and marker designed based on the mutation site in candidate gene was validated to be promising in marker-assisted selection (MAS) for melon breeding

Methods

Results

Conclusion