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

Abstract

Summary 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.

Some rootstocks improve pepper tolerance to mild salinity through ionic regulation

“…There is evidence that photosynthesis regulates nitrate reduction by modulating NR activity [64,65], which agrees with the results presented herein, which indicate that salt application diminishes A N and NR activity. The most tolerant rootstock (A/12) in A N terms exhibited lower NR inhibition if compared with the others.…”

Populus deltoides females are more selective in nitrogen assimilation than males under different nitrogen forms supply

“…The concentrations of nitrogen (N) and carbon (C) were determined by the semi-micro Kjeldahl method (Mitchell 1998) and the rapid dichromate oxidation technique (Nelson and Sommers 1982), respectively. The total C to N ratio (C/N) was calculated as an estimate of the long-term nitrogen use efficiency (Livingston et al 1999 Yousfi et al (2012). The nitrogen isotope composition was expressed as d 15 N (Coplen 2008).…”

Nutrición mineral y fotosíntesis en plántulas de algarrobo blanco, Prosopis alba (Fabaceae), en estrés salino

“…Este paso clave en la asimilación del nitrógeno, es catalizado por la nitrato reductasa, produciendo nitrito, que posteriormente es reducido a amonio (Yousfi et al, 2012). La respuesta de la actividad NR de plántulas crecidas en presencia de NaCl, se caracterizó por un rápido incremento inicial, seguido por una importante inhibición a partir del cuarto día de tratamiento ( Fig.…”

“…El efecto de la salinidad sobre la actividad nitrato reductasa depende de muchos factores, tales como la especie, fuente de nitrógeno, edad de la planta, concentración salina, y tiempo de exposición al estrés. Se ha reportado una disminución significativa en la actividad NR en hojas de Brassica juncea (Siddiqui, Mohammad, Khan, Mohamed & Al-Whaibi 2012), genotipos sensibles de trigo (Carillo et al, 2008;Yousfi, Serret, Márquez, Voltas & Araus, 2012), tomate (Gong et al, 2013), algodón (Kawakami, Osterhuis & Snider, 2013), girasol , Vigna unguiculata (Magalhães de Aragão, Silva, Lima & Silveira, 2011) y hojas y raíces de álamo (Ehlting et al, 2007) sometidas a estrés con NaCl. Por el contrario, el estrés salino incrementó la actividad nitrato reductasa en raíces de pepino (Reda, Migocka & Klobus, 2011) y tomate (Debouba, Maâroufi-Dghimi, Suzuki, Ghorbel & Gouia, 2007).…”