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Combined use of δ13C, δ18O and δ15N tracks nitrogen metabolism and genotypic adaptation of durum wheat to salinity and water deficit

Yousfi, Salima, Serret, Maria Dolores, Márquez, Antonio José, Voltas, Jordi, Araus, José Luis
The new phytologist 2012 v.194 no.1 pp. 230-244
acclimation, adaptation, biomass, breeding, carbon, drought tolerance, durum wheat, genotype, glutamate-ammonia ligase, ions, irrigation management, nitrate reductase, nitrogen, nitrogen content, nitrogen metabolism, oxygen, plants, saline water, salinity, stable isotopes, water stress
• Accurate phenotyping remains a bottleneck in breeding for salinity and drought resistance. Here the combined use of stable isotope compositions of carbon (δ13C), oxygen (δ18O) and nitrogen (δ15N) in dry matter is aimed at assessing genotypic responses of durum wheat under different combinations of these stresses. • Two tolerant and two susceptible genotypes to salinity were grown under five combinations of salinity and irrigation regimes. Plant biomass, δ13C, δ18O and δ15N, gas‐exchange parameters, ion and N concentrations, and nitrate reductase (NR) and glutamine synthetase (GS) activities were measured. • Stresses significantly affected all traits studied. However, only δ13C, δ18O, δ15N, GS and NR activities, and N concentration allowed for clear differentiation between tolerant and susceptible genotypes. Further, a conceptual model explaining differences in biomass based on such traits was developed for each growing condition. • Differences in acclimation responses among durum wheat genotypes under different stress treatments were associated with δ13C. However, except for the most severe stress, δ13C did not have a direct (negative) relationship to biomass, being mediated through factors affecting δ18O or N metabolism. Based upon these results, the key role of N metabolism in durum wheat adaptation to salinity and water stress is highlighted.