Uncovering the genetic architecture of Colletotrichum lindemuthianum resistance through QTL mapping and epistatic interaction analysis in common bean.

Ana M González,Carmen Capel,Fernando J Yuste-Lisbona,A Paula Rodiño,Antonio M De Ron,Rafael Lozano,Marta Santalla,Manuel García-Alcázar

doi:10.3389/fpls.2015.00141

Ana M González, Carmen Capel + Show 6 more

Open Access

https://doi.org/10.3389/fpls.2015.00141

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Abstract

Colletotrichum lindemuthianum is a hemibiotrophic fungal pathogen that causes anthracnose disease in common bean. Despite the genetics of anthracnose resistance has been studied for a long time, few quantitative trait loci (QTLs) studies have been conducted on this species. The present work examines the genetic basis of quantitative resistance to races 23 and 1545 of C. lindemuthianum in different organs (stem, leaf and petiole). A population of 185 recombinant inbred lines (RIL) derived from the cross PMB0225 × PHA1037 was evaluated for anthracnose resistance under natural and artificial photoperiod growth conditions. Using multi-environment QTL mapping approach, 10 and 16 main effect QTLs were identified for resistance to anthracnose races 23 and 1545, respectively. The homologous genomic regions corresponding to 17 of the 26 main effect QTLs detected were positive for the presence of resistance-associated gene cluster encoding nucleotide-binding and leucine-rich repeat (NL) proteins. Among them, it is worth noting that the main effect QTLs detected on linkage group 05 for resistance to race 1545 in stem, petiole and leaf were located within a 1.2 Mb region. The NL gene Phvul.005G117900 is located in this region, which can be considered an important candidate gene for the non-organ-specific QTL identified here. Furthermore, a total of 39 epistatic QTL (E-QTLs) (21 for resistance to race 23 and 18 for resistance to race 1545) involved in 20 epistatic interactions (eleven and nine interactions for resistance to races 23 and 1545, respectively) were identified. None of the main and epistatic QTLs detected displayed significant environment interaction effects. The present research provides essential information not only for the better understanding of the plant-pathogen interaction but also for the application of genomic assisted breeding for anthracnose resistance improvement in common bean through application of marker-assisted selection (MAS).

Highlights

Members of the ascomycete genus Colletotrichum cause devastating anthracnose diseases in many agronomically important crops in temperate, tropical and subtropical regions (Bailey and Jeger, 1992)
The pathogen has a sequential biotrophicand necrotrophic-infection process to invade and colonize the plant hosts, that involves the transition from an asymptomatic biotrophic phase to a destructive necrotrophic phase referred to as the biotrophynecrotrophy switch, which is essential for anthracnose disease development (Bhadauria et al, 2011)
Biological Material A recombinant inbred lines (RIL) population consisting of 185 F7 lines was developed by single-seed descent from an F2 population from the cross between PMB0225 and PHA1037 accessions belonging to the Andean gene pool

Summary

Introduction

Members of the ascomycete genus Colletotrichum cause devastating anthracnose diseases in many agronomically important crops in temperate, tropical and subtropical regions (Bailey and Jeger, 1992). The damage caused by this fungus in bean crops is so great that it has produced an economical loss in productive countries (Vigidal-Filho et al, 2007). C. lindemuthianum causes a hypersensitive response in bean resistant plants - groups of red-brownish wounds of different sizes that are produced by the plant to delimit the spread of the pathogenic fungus (Martínez-Pacheco et al, 2009). The process of co-evolution between the fungus and bean resistant plants has led this fungal species to produce new pathogenic variants, which can be detected on the basis of the phenotypic response to anthracnose infection shown by different varieties of common bean (Melotto et al, 2000; Rodríguez-Guerra et al, 2003). More than 100 races have been described for C. lindemuthianum (RodríguezGuerra et al, 2003) and new pathotypes are reported every day, indicating a large pathogenic variability of this fungus

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