IBIP seminar – « fruit and seed »

Thursday, March 24, 2016

Control of seed quality traits in legumes: from model to crop species

Karine Gallardo
Déterminismes Génétiques et Environnementaux de l’Adaptation des Plantes à des Systèmes de culture Innovants, INRA Dijon

The capacity of legume seeds to accumulate large amounts of proteins during their development makes them an excellent protein source for both animal and human nutrition. One major focus of our work has been to dissect the molecular processes active in legume seed development as a crucial step towards seed quality improvement. To enable the identification of key genes potentially involved, we have previously developed a series of omics resources related to seed development and to specific seed tissues or cell compartments in the model legume Medicago truncatula. These omics data were anchored to a genetic map of M. truncatula that weused to detect QTLs for seed weight and composition. QTL regions syntenic between M. truncatula and pea (Pisum sativum) were identified and several candidate genes that can function as leads for improvement of seed quality traits were tested by means of TILLING mutants in both species. Several of these genes were specifically expressed in the seed endosperm, demonstrating the key role of this tissue in the determinism of seed size in legumes. Others were related to sulfate transport and metabolism. As legume seed proteins contain limiting proportions of cysteine and methionine, we decided to investigate further the role of sulfur nutrition in the establishment of seed quality. For this, we are studying the pea crop, which now benefits from extensive genomics and post-genomics resources. Transcriptomics studies of vegetative leaves (i.e. a major source of nutrients for seeds), using microarrays developed for pea, revealed many genes to be significantly up-regulated in response to sulfur deficiency. The roles of some of these genes are now being examined. Using pea mutants for the vacuolar sulfate transporter SULTR4;1 gene, we recently demonstrated that the impressive plasticity of legumes in their response to sulfur deficiency relies on vacuolar sulfate transport activities, and hence on the capacity of legume plants to store sulfate during the vegetative phase and then to mobilize this sulfur reserve in low-sulfate environments.

Contact : Cathy Curie

Contacts IBIP :
Sabine Zimmermann
Alexandre Martiniere
Christine Granier
Chantal Baracco