Fine mapping of the major anthracnose resistance QTL AnRGO5 in Capsicum chinense \u2018PBC932\u2019

Yuanyuan Zhao,Lihao Wang,Yiwei Liu,Hailong Yu,Zhenghai Zhang,Baoxi Zhang,Wenwen Ma,Risheng Wang,Yacong Cao,Jie Gao

doi:10.1186/s12870-019-2115-1

Abstract

BackgroundColletotrichum species are the causal agents of anthracnose, a major disease affecting the yield and quality of pepper (Capsicum spp.). Colletotrichum scovillei is widespread in China, has strong pathogenicity and drug resistance, and causes anthracnose disease in pepper fruits that severely reduces production. Previously, an anti-anthracnose locus AnRGO5 was mapped to the P5 chromosome on the basis of analyses of fruit at the green mature stage. The aim of this study was to narrow down the interval of this locus and identify the gene responsible for conferring resistance.ResultsOn the basis of results of re-sequencing of Capsicum chinense ‘PBC932’ and C. annuum ‘77013’, we developed Kompetitive allele-specific PCR (KASPar) markers and insertion–deletion (InDel) markers linked to AnRGO5 at the green mature fruit stage and used them to construct a genetic linkage map (42 markers, 24.4 cM in length). Using data obtained in phenotypic and genotypic analyses of BC4S1, BC4S2, and BC4S3 populations, AnRGO5 was located between the markers P5in-2266-404 and P5in-2268-978 within a physical distance of 164 kb. This region contained five genes, including CA05g17730. CA05g17730 encodes ‘R1C-3-like’ putative late blight resistance protein homologs. The transcript level of CA05g17730 differed between ‘PBC932’ and ‘77013’. The structure of the CA05g17730 gene also differed between ‘PBC932’ and ‘77013’.ConclusionsWe narrowed down the QTL interval to a region containing five genes. These results will be useful for further research on the mechanisms of resistance to anthracnose, and for marker assisted selection for anthracnose-resistant capsicum lines.

Highlights

Colletotrichum species are the causal agents of anthracnose, a major disease affecting the yield and quality of pepper (Capsicum spp.)
We narrowed down the major Quantitative trait locus (QTL) resistant to C. scovillei interval to a 164 Kb region containing five genes
Homologe and transcript analyses indicated that CA05g17730 is the suspect candidate gene conferring resistance to C. scovillei at the mature green fruit stage of pepper

Summary

Introduction

Colletotrichum species are the causal agents of anthracnose, a major disease affecting the yield and quality of pepper (Capsicum spp.). Colletotrichum scovillei is widespread in China, has strong pathogenicity and drug resistance, and causes anthracnose disease in pepper fruits that severely reduces production. Anthracnose disease is one of the major economic constraints to pepper (Capsicum spp.) production worldwide, especially in tropical and subtropical regions [1]. Agricultural control to remove diseased fruit and clear drainage ditches is very labor intensive. There is still little information available about the interactions between the host and the causal pathogens of pepper anthracnose [12]. Breeding for anthracnose resistance has been attempted in Asia for more than 20 years with little success [13]

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