Genetic diversity of nodulated root structure in a very diverse pea collection
Résumé
The root system is responsible for nitrogen (N) acquisition, which in legumes, combines mineral acquisition and symbiotic fixation in nodules. Despite these two complementary pathways, N nutrition may be a limiting factor of legumes yield because nodules are very sensitive to their local environment and N fixing legume root system is poorly developed which may limit soil exploration [1]. Pea establishes in root nodules a symbiotic association with Rhizobium leguminosarum sv viciae bacteria (Rlv) [2]. This study assessed the potential of naturally occurring genetic variability of nodulated root structure and functioning traits to improve yield pea performance. Two successive glasshouse experiments were performed on a wide 336-pea panel consisted of wild, landraces and cultivars from diverse geographic origins [3]. Plants were inoculated by a mixture of strains representative of the Rlv diversity and grown in innovative RhizoTubes© on the 4PMI high throughput phenotyping platform allowing daily automatic imaging of shoots and nodulated root systems and their analysis [4]. Significant variations between pea accessions were observed for traits describing shoot and nodulated root system architecture. After genotyping of the pea panel by exome capture, genome wide association analyses were performed using 3.9 millions SNPs to identify the genetic determinants of these traits. They will be useful for breeding new pea cultivars with increased root system size, sustained nodule number, and improved N nutrition.