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RESEARCH PRODUCT

Genetic diversity of nodulated root structure and nitrogen nutrition in a core collection of pea

subject

description

Pea (Pisum sativum) is the third most important grain legume worldwide, and the increasing demand for protein-rich raw material for animal feed or human nutrition has led to a greater interest in this crop as a protein source. Moreover, legumes do not need nitrogen (N) fertilizers, thanks to their natural ability to use, as main N resource, the atmospheric N2 from symbiosis in nodules with Rhizobiaceae spp. However, N nutrition can still be a limiting factor of yield and seed quality in legumes because nodules are very sensitive to their local environment, in particular to nitrate, and root systems of N2 fixing legumes are poorly developed, which makes them unable to explore a large soil volume and sensitive to unfavourable conditions. This study assessed the potential of naturally occurring genetic variability of nodulated root structure and functioning traits to improve yield pea performance. Glasshouse experiments were performed on a core collection of 104 pea accessions, including 44 old or released cultivars, 10 inbred lines, 28 landraces and 22 semi-natural or wild genotypes. They were selected from the French pea collection based on their genetic diversity and agronomic traits. An analysis of the structure of the French pea collection was performed with the software DaPC based on 353 SNPs markers. The results showed that the material in the core collection could be assigned to 7 distinct genetic groups. A significant positive relationship was found between nodule, root and N nutrition traits. Significant variations between accessions were observed for most traits describing the nodulated root structure and which were obtained from measurements and root image analysis (root number, length and biomass, nodule number and biomass). Significant variations between accessions were also observed for carbon and N acquisition traits, estimated respectively from leaf surface area, shoot biomass and N content and nitrogen fixation measurement. Further analyses will be performed to understand the associations between molecular and nodulated root structure or functioning diversity. They will be useful for breeding new pea cultivars with increased root system size, sustained nodule number, and improved N nutrition.