Genetic Architecture of Chile Pepper (Capsicum Spp.) QTLome Revealed Using Meta-QTL Analysis

Abstract

Chile peppers (Capsicum spp.) are among the most important vegetable crops in the world due to their health-related, economic, and industrial uses. In recent years, quantitative trait loci (QTL) mapping approaches have been widely implemented to identify genomic regions affecting variation for different traits for marker-assisted selection (MAS) in peppers. Meta-QTL analysis for different traits in Capsicum remains lacking, and therefore it would be necessary to re-evaluate identified QTL for a more precise MAS for genetic improvement. We report the first known meta-QTL analysis for diverse traits in the chile pepper QTLome. A literature survey using 29 published linkage mapping studies identified 766 individual QTL from five different trait classes. A total of 311 QTL were projected into a consensus map. Meta-analysis identified 30 meta-QTL regions distributed across the 12 chromosomes of Capsicum. MQTL5.1 and MQTL5.2 related to Phytophthora capsici fruit and root rot resistance were delimited to < 1.0 cM confidence intervals in chromosome P5. Candidate gene analysis for the flanking sequences for the P5 meta-QTL revealed biological functions related to DNA repair and transcription regulation. Moreover, epigenetic mechanisms such as histone and RNA methylation and demethylation were predicted, indicating the potential role of epigenetics for P. capsici resistance. Allele specific SNP markers for the meta-QTL will be developed and validated using different breeding populations of Capsicum for MAS of P. capsici resistant lines. Altogether, results from meta-QTL analysis for chile pepper QTLome rendered further insights into the genetic architecture of different traits for this valuable horticultural crop.