Using stable isotope natural abundances (δ15N and δ13C) to integrate the stress responses of wild barley (Hordeum spontaneum C. Koch.) genotypes

Abstract

To integrate the complex physiological responses of plants to stress, natural abundances (delta) of the stable isotope pairs 15N/14N and 13C/12C were measured in 30 genotypes of wild barley (Hordeum spontaneum C. Koch.). These accessions, originating from ecologically diverse sites, were grown in a controlled environment and subjected to mild, short-term drought or N-starvation. Increases in total dry weight were paralleled by less negative delta 13C in shoots and, in unstressed and droughted plants, by less negative whole-plant delta 13C. Root delta 15N was correlated negatively with total dry weight, whereas shoot and whole-plant delta 15N were not correlated with dry weight. The difference in delta 15N between shoot and root varied with stress in all genotypes. Shoot-root delta 15N may be a more sensitive indicator of stress response than shoot, root or whole-plant delta 15N alone. Among the potentially most productive genotypes, the most stress-tolerant had the most negative whole-plant delta 15N, whether the stress was drought or N-starvation. In common, controlled experiments, genotypic differences in whole-plant delta 15N may reflect the extent to which N can be retained within plants when stressed.

The nutrient status of epiphytes and their host trees along an elevational gradient in Costa Rica

“…While d 15 N signatures have successfully been used to interpret source nutrients (Dawson et al 2002;Robinson et al 2000), we found our data difficult to interpret because of the high variability and lack of consistent patterns within or among epiphyte taxa (Fig. 4b).…”

“…4b). This high variability is likely a combination of source nutrient signature, a possible series of integrated fractionation events (Dawson et al 2002;Robinson et al 2000), and variability among species within each taxon. The most notable result for d 15 N values was the depletion trend with increasing elevation in host trees.…”

Physiological and molecular analyses of seedlings of two Tunisian durum wheat (Triticum turgidum L. subsp. Durum [Desf.]) varieties showing contrasting tolerance to salt stress

“…Salt tolerance in cultivated wheat can be improved by using the allelic repertoire offered by wheat wild relatives. For this reason, the existing variability currently available in gene pools must first be characterized at physiological, morphological and genetic levels (Robinson et al 2000;Nevo 2001).…”

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

“…An array of salinity-drought combinations modifies d 15 N in shoots and roots relative to controls, with tolerant genotypes exhibiting higher shoot d 15 N than susceptible genotypes (Table S1), suggesting that stress conditions influence N uptake and ⁄ or assimilation (Handley et al, 1997;Ellis et al, 2002;Yousfi et al, 2009Yousfi et al, , 2010 reported in cereals as a response to salinity (Yousfi et al, 2009(Yousfi et al, , 2010 and deficit irrigation (Robinson et al, 2000;Raimanová & Haberle, 2010). Reduced g s as a result of either salinity or water stress, or a combination of both, would lead to a reduction in the loss of ammonia and nitrous oxide, hence decreasing d 15 N (Farquhar et al, 1980;Smart & Bloom, 2001).…”