Abstract

Cultivated peanut (Arachis hypogaea L.) is an important oilseed crop that is grown extensively in Africa, Asia and America. The diseases early and late leaf spot severely constrains peanut production worldwide. Because multiple genes control resistance to leaf spot diseases, conventional breeding is a time-consuming approach for pyramiding resistance genes into a single genotype. Marker-assisted selection (MAS) would complement and accelerate conventional breeding once molecular markers tightly associated with the resistance genes are identified. In this study, we have generated a large number of SNPs through genotyping by sequencing (GBS) and constructed a high-resolution map with an average distance of 1.34 cM among 2,753 SNP markers distributed on 20 linkage groups. QTL mapping has revealed that major QTL within a confidence interval could provide an efficient way to detect putative resistance genes. Analysis of the interval sequences has indicated that a major QTL for resistance to late leaf spot anchored by two NBS-LRR resistance genes on chromosome B05. Two major QTLs located on chromosomes A03 and B04 were associated with resistance genes for early leaf spot. Sequences within the confidence interval would facilitate identifying resistance genes and applying marker-assisted selection for resistance.

Highlights

  • Leaf spot (ELS) caused by Cercospora arachidicola S

  • Partially resistant to tomato spotted wilt virus (TSWV) and stem rot caused by Sclerotium rolfsii, this variety is susceptible to Early leaf spot (ELS)

  • The most common symptom of early leaf spot was identified by brown lesions surrounded by a yellow color on the upper side of leaves and the most common symptom of late leaf spot was detected by dark brown lesions showed on the underside of affected leaves

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Summary

Introduction

Leaf spot (ELS) caused by Cercospora arachidicola S. Epidemics of leaf spot diseases may result in partial to complete defoliation, which can lead to losses of up to 50% of anticipated yields (Branch and Culbreath, 2013). Epidemics of leaf spot were less severe using strip than conventional tillage, QTLs for Resistance to Leaf Spots in Peanut fungicide treatments are still needed (Cantonwine et al, 2007). The development of leaf spot resistant cultivars is desirable and sustainable strategy to control the leaf spot diseases, which could result a reduction in the amount and frequency of fungicide applications needed to control both diseases (Shoba et al, 2012; Branch and Culbreath, 2013)

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