EUCLEG 2021

Deciphering the ecophysiological and molecular mechanisms underlying the interaction between sulfur nutrition and the response of pea to water stress when nitrogen nutrition relies exclusively on symbiotic nitrogen fixation

You can access the project (code, figure, explanation …) through this link

A first experiment, conducted from March to July 2021, aimed to elucidate the ecophysiological and molecular mechanisms underlying the interaction between sulfur (S) nutrition and the response of pea (Pisum sativum) to water stress under nitrogen (N) nutrition exclusively relying on symbiotic nitrogen fixation. Four genotypes were studied: two wild-types with contrasting resilience to water stress (Kayanne and Caméor) and two TILLING mutants of the vacuolar sulfate transporter gene (SULTR4) in the Caméor background, which are unable to use vacuolar sulfate. Plants were cultivated in the 4PMI platform with rhizobia, excluding nitrate, under four experimental conditions: (i) sufficient water and sulfur supply, (ii) moderate water stress (40% maximum water retention) for two weeks, (iii) sulfur deprivation, and (iv) combined water and sulfur stresses. Tissue compartments were collected at four time points: pre-stress (E0), end of stress (E1, early flowering), recovery (E2, 10 days post-stress), and maturity (Emat). Stress effects on plant growth and development were pronounced, particularly in Caméor. Principal component analysis of 14 aerial morphological and physiological variables at E1 clearly separated double-stressed plants from controls, with stress effects persisting during recovery. These findings highlight sulfur’s critical role in maintaining water stress resilience when nitrogen fixation is the sole nitrogen source. Elemental analyses (C, N, S) will investigate nutrient allocation strategies under combined and individual stresses. Additionally, molecular analyses of roots, nodules, vegetative, and reproductive leaves at E0, E1, and E2 were conducted. Root and leaf tissues underwent RNA sequencing to identify candidate genes for improving water and nutrient uptake, remobilization, and seed yield plasticity. These transcriptomics data will further prioritize GWAS-derived genes linked to seed yield resilience under abiotic stresses. This study provides a foundation for understanding sulfur’s contribution to water stress resilience in symbiotic nitrogen fixation systems and informs future breeding strategies for improved legume performance under combined nutrient and water constraints.