Characterization of pea defense mechanisms against Fusarium oxysporum

Abstract

Fusarium oxysporum f. sp. pisi (Fop) is a ubiquitous soil pathogen reducing field pea (Pisum sativum) yield worldwide. Monogenic resistance have been already described and successfully used in breeding. However, monogenic resistance is at risk of breakdown by the constant evolution of the pathogen. To improve the durability of resistance, the genetic base of resistance should be broadened and a better knowledge on the defense mechanisms efficient against Fop should be gathered. To this aim, we identified several Fop-resistant Pisum spp. accessions and characterized the underlying defense mechanisms. A first study on pre-penetration mechanism revealed that the root exudate of three accessions inhibited Fop germination. Further analyses indicated that this pre-penetration mechanism was mainly mediated through the constitutive secretion of pisatin, the main pterocarpan pea phytoalexin. A second study focused on post-penetration defense mechanism at the cellular level, showing that involvement of three main mechanisms, namely papilla formation, cell walls strengthening and accumulation of phenols and carbohydrates. These studies highlight that pea accessions combined several strate gies to delay and efficiently prevent disease development which offer interesting opportunities for breeding.