Genome-wide association study reveals a set of genes associated with resistance to the Mediterranean corn borer (Sesamia nonagrioides L.) in a maize diversity panel.

Luis Samayoa,Rosa Malvar,Bode A Olukolu,James B Holland,Ana Butrón

doi:10.1186/s12870-014-0403-3

Abstract

BackgroundCorn borers are the primary maize pest; their feeding on the pith results in stem damage and yield losses. In this study, we performed a genome-wide association study (GWAS) to identify SNPs associated with resistance to Mediterranean corn borer in a maize diversity panel using a set of more than 240,000 SNPs.ResultsTwenty five SNPs were significantly associated with three resistance traits: 10 were significantly associated with tunnel length, 4 with stem damage, and 11 with kernel resistance. Allelic variation at each significant SNP was associated with from 6 to 9% of the phenotypic variance. A set of genes containing or physically close to these SNPs are proposed as candidate genes for borer resistance, supported by their involvement in plant defense-related mechanisms in previously published evidence. The linkage disequilibrium decayed (r2 < 0.10) rapidly within short distance, suggesting high resolution of GWAS associations.ConclusionsMost of the candidate genes found in this study are part of signaling pathways, others act as regulator of expression under biotic stress condition, and a few genes are encoding enzymes with antibiotic effect against insects such as the cystatin1 gene and the defensin proteins. These findings contribute to the understanding the complex relationship between plant-insect interactions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0403-3) contains supplementary material, which is available to authorized users.

Highlights

Corn borers are the primary maize pest; their feeding on the pith results in stem damage and yield losses
This study focuses on the noctuid Mediterranean corn borer (MCB) Sesamia nonagroides Lefebvre, the most important insect pest of maize in the Mediterranean region that includes Southern Europe [2,5,6]
Analysis of variance and heritabilities Differences among inbred lines were highly significant (P < 0.01) for all resistance (TL, stem damage (SD), and KR) and agronomic traits (PH, days to anthesis (DTA), and days to silking (DTS)); while significant (P < 0.05) genotype by environment (G × E) interactions were observed for all traits as shown in Additional file 1: Table S1 and S2

Summary

Introduction

Corn borers are the primary maize pest; their feeding on the pith results in stem damage and yield losses. Corn borers feeding on the pith of the stem results in yield losses because stem damage interferes with assimilate movement to developing kernels. They can attack the ears, promoting secondary fungal infection, leading to contamination of grain with mycotoxins that may affect human and animal health [3,4]. There are different species of borers that attack maize in different parts of the world. The most economically important species are classified into two families: Crambidae and Noctuidae. Within the Crambidae family, the Samayoa et al BMC Plant Biology (2015) 15:35

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