Abréviations

Abstract

Pea ( Pisum sativum ) is a legume with high potential for animal and human nutrition as well as agronomic values. Aphanomyces root rot caused by Aphanomyces euteiches is a major disease of pea. No method of control is currently available but breeding for resistant varieties is promising since many advances have been made in the identification and validation of QTL, Quantitative Trait Locus, in the last twenty years. In order to anticipate the sustainable deployment of QTL in future pea varieties, this study aimed to evaluate in a 4 year-infested field assay the evolution of soil inoculum potential (IP) and aggressiveness of A. euteiches populations, in successions of pea NILs and fababean varieties grown in single or alternate cropping systems. The IP analysis of 52 soils annually sampled between 2016 and 2019 from micro-plots of 13 different successions showed that the IP was lower in soils cultivated with partially resistant peas genotypes, especially one NIL carrying the major QTL Ae-Ps7.6 , and also in soils grown with alternating pea and fababean. The analysis of A. euteiches aggressiveness was carried out using 84 A. euteiches isolates isolated in 2016 and 2019 from a single crop succession of a pea NIL carrying a combination of the major QTL Ae-Ps7.6 and a minor QTL. Results showed that the proportion of the most aggressive isolates identified was higher in A. euteiches populations isolated in 2019 than on populations isolated in 2016.