Genome-wide association mapping of the architecture of susceptibility to the root-knot nematode Meloidogyne incognita in Arabidopsis thaliana

Susceptibility to the root-knot nematode Meloidogyne incognita in plants is thought to be a complex trait based on multiple genes involved in cell differentiation, growth, and defence. Previous genetic analyses of susceptibility to M. incognita have mainly focussed on segregating dominant resistance genes in crops. It is not known if plants harbour significant genetic variation in susceptibility to M. incognita independent of dominant resistance genes. To study the genetic architecture of susceptibility to M. incognita in plants, we analysed nematode reproduction on a highly diverse set of 340 natural inbred lines of Arabidopsis thaliana with genome-wide association mapping. We observed a surprisingly large variation in nematode reproduction among these lines. Genome-wide association mapping revealed thirty-six quantitative trait loci (QTLs) in the genome of A. thaliana significantly associated with reproductive success of M. incognita. Mutant analysis of candidate genes located in four QTLs revealed various novel proteins functioning as (co-)regulators of susceptibility to M. incognita in Arabidopsis. Our data further suggests that breeding for loss-of-susceptibility, based on allelic variants critically involved in nematode feeding, could be used to make crops more resilient to root-knot nematodes.