The project will tackle one of the most severe problems in protein production: A phenomenon called soil or legume fatigue caused by a complex of soil-borne pathogens. Root and foot diseases in legumes, especially in pea, cause severe damage and can lead up to total yield loss. The lack of adequate resistance in current pea varieties impedes pea cultivation worldwide. Sustainable solutions are needed particularly for organic farmers who rely on this ecologically important nitrogen fixator.
The overall goal is to improve the resistance of pea against soil-borne diseases to allow higher cultivation frequencies of grain legumes. Investigating the potential role of root exudates in the inhibition or attraction of plant pathogens as well as beneficial microbes will elucidate the physiological basis of the resistance of pea genotypes against soil fatigue.
In a recent report by the European Commission, it was highlighted that "… the use of protein crops in arable rotations has high potential to increase the resource efficiency and environmental performance of European cropping (soil quality and health, nitrogen management, agro-biodiversity, reduction of greenhouse gas emissions) for all value-chain scale levels involved" (Schreuder and De Visser 2014). Despite an increasing demand for protein crops, the world production of the second most widely grown legume, pea, is declining (FAO 2013). In the European Union alone, production and yield (per ha) decreased between 2005 and 2012 by 49 % and 22 %, respectively. Increasing problems with fungal diseases are a main cause for the decline in yield (Fuchs et al. 2014; Wilbois et al. 2013). In Canada, yield reduction from root rot alone has been reported to be as high as 60 % (Chang et al. 2013), while blights in Australia can cause yield reductions of 75 % (Davidson 2012). Up to now, there have been no pea cultivars with sufficient resistance to a range of important pathogens such as Aphanomyces euteiches, Pythium spp., Fusarium oxysporum, F. solani, F. avenaceum, Rhizoctonia solani, Phoma pinodella, and Didymella pinodes (Baćanović 2015; Bardin et al. 2004; Castillejo et al. 2015; Chang et al. 2013; Hamon et al. 2013; Mathew et al. 2012).
The yield decline of pea affects organic production systems in particular due to the crucial role of this nitrogen-fixing legume in crop rotations. In order to facilitate a higher frequency of grain legumes in (organic) farming systems, a better understanding of the complex interactions between the plant and various soil-borne pathogens is urgently needed. This will aid in the development of screening tools for breeders to select genotypes resistant to soil-borne diseases taking account of the complex plant-soil interface. Breeding pea varieties with high resilience against soil/legume fatigue is a precondition for obtaining high and stable protein yields and is, therefore, crucial for the acceptance of farmers. Soil-borne pathogens of pea also affect other legumes like faba bean, lupin and fodder crops. Therefore, resistant pea varieties will help to reduce the cultivation break of legumes in general. Ultimately, outcomes of this project will be transferable to other legume cultivation systems.