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

Legumes are able to improve soil fertility via a mutualistic symbiosis with nitrogen-fixing rhizobacteria. Therefore, they represent ecologically important crops for sustainable farming systems. Besides their ecological function, grain legumes considerably contribute to the dietary protein N needs of humans (Graham and Vance 2003). Despite their importance, legume cultivation remains low due to low and unstable yields (Rubiales and Mikic 2015). Soil fatigue, also called legume yield depression syndrome, is caused by a complex of different soil-borne pathogens and thought to be the main reason for these yield losses, especially in pea (Pisum sativum) (Fuchs et al. 2014). The overall goal of this project is to improve the resistance of pea against soil-borne diseases. More than 250 pea lines (varieties, advanced breeding material and GenBank accessions) will be screened for resistance in standardised growth chamber experiments and on-farm. A screening tool for breeders will be developed in collaboration with Getreidezüchtung Peter Kunz. The role of root exudates in shaping the plants’ own detrimental or beneficial microbial community in the rhizosphere will be investigated by HPTLC in collaboration with Giessen University, Germany, and CAMAG, Switzerland. Key pathogens and beneficials will be characterised by quantitative real-time PCR and linked to root exudate profiles of pea varieties with contrasting resistance levels. In addition, we will identify resistance associated quantitative trait loci via genome-wide association study. Our study will shed light on the complex interactions between pea and soil microbes and promote resistance breeding programmes for legumes. This project is supported by the Mercator Foundation Switzerland and the Swiss Federal Office of Agriculture