Improving disease resistance of pea through selection at the plant-soil interface

Summary

Pea (Pisum sativum L.) belongs to the legume family (Fabaceae). Legumes form mutualistic symbiosis with nitrogen fixing rhizobacteria and, thereby, are able to improve soil fertility. Legume crops are important protein source for food and feed and contribute to the nitrogen demand of succeeding crops. Despite their importance, cultivation of cool-season legumes in temperate zones remains below expectations due to low and unstable yields. Soil fatigue is caused by a complex of different soil-borne pathogens and thought to be the main reason for yield losses, especially in pea. Plants have the ability to actively shape the community of root associated microbes through root exudations. Evidence is growing that there is considerable genetic variation for plant traits involved in the regulation of plant-microbe interactions, and that these genetic resources can be exploited by plant breeders. The overall goal of this project is to improve resistance of pea against soil-borne diseases. So far, more than 300 pea accessions have been screened for resistance in a standardised growth chamber pot-experiment and a subset of susceptible and tolerant pea genotypes has been identified. The results of the pot-experiment will be verified in on-farm trials with repeated pea cultivation in the recent crop rotation history or clear evidence for soil fatigue. In a next step, key pathogens and beneficials will be assessed by quantitative real-time PCR and linked to root exudate profiles of pea varieties with contrasting resistance levels. The role of root exudates in shaping the plants’ own detrimental or beneficial microbial community in the rhizosphere will be investigated using High-Performance-Thin-Layer-Chromatography. Furthermore, we will identify resistance associated quantitative trait loci (QTL) via genome-wide association study. The study will shed light on the complex interactions between pea and soil microbes and promote resistance breeding programmes for legumes.