Comparative genome-wide-association mapping identifies common loci controlling root system architecture and resistance to <em>Aphanomyces euteiches</em> in pea

BAP GEAPSI INRAInternational audiencePlant architecture can contribute to decrease plant susceptibility to pathogens by favoring mechanisms leading to infection escape or increased tolerance. Combining genetic resistance with architectural traits that can negatively impact disease development is thus a strategy of great interest to reduce epidemics. Until now, most strategies exploiting plant architecture have focused on the aerial parts of plants. Few studies have been done on the identification of root system architecture (RSA) traits limiting root disease development and even less on their use in breeding. Aphanomyces euteiches, a soil-borne pathogen infecting roots, is a major limiting factor of pea crop yield. Consistent quantitative trait loci controlling partial resistance were identified in this species [1,2], and other studies reported its RSA as highly variable and under polygenic control [3]. However, the contribution of RSA to resistance to A. euteiches has not yet been explored in pea. To identify common loci controlling RSA and resistance to A. euteiches, we performed a genome wide association (GWA) study using a collection of 266 pea lines contrasted for root architecture or Aphanomyces root rot resistance. The study used recent 14,157 Single Nucleotide Polymorphism resources developed in pea [4,5]. The collection was phenotyped in controlled conditions and using image analysis. The GWA study identified precise genomic regions controlling RSA and common loci associated with resistance to A. euteiches, opening prospects in mining RSA loci in breeding to limit Aphanomyces root rot severity on pea