Physiology of salinity tolerance in Bromus danthoniae genotypes originated from saline and non-saline areas of West Iran

Abstract

Genetic resources of halophytic grass species are vital factors to be explored for improvement in pasture and rangeland productivity and to elucidate mechanisms of salinity tolerance. The objective of the present study was to understand the adaptive strategies of Bromus danthoniae to a hyper-saline environment by using 80 genotypes originated from saline and non-saline areas in West Iran. Salinity treatments of 0 and 350 mm NaCl were applied for 4 weeks, and plant growth, leaf water status, ionic status, oxidative stress and salt-excretion responses were evaluated. Analysis of variance showed significant genotypic (G) variation for all traits as well as significant salinity stress (S) and G × S effects for most of the traits. Dry matter was positively correlated with K+/Na+ (r = 0.69) and Ca2+/Na+ (r = 0.66) ratios, and negatively correlated with Na+ concentration (r = –0.72). In addition, a coincidence of low concentrations of Na+ in the leaf tissues and the excretion of salt crystals on the sheath leaves and leaf blades was observed in the hyper-salinity tolerant genotypes. These observations open up new avenues for elucidating potential strategies and pathways used by halophytic grasses to avert the excess Na+ in their plant tissues.

Salinity tolerance of wild barley Hordeum vulgare ssp. spontaneum

“…n 43, n 23 and n 27) accumulated much lower Na in the leaves and roots, as compared to those of salinity‐sensitive genotypes (cultivars and a few wild barley genotypes). These findings were consistent with the previous studies on the wild grasses in which the critical role of the sodium (Na) ion in salinity tolerance has been highlighted, particularly at high levels of salinity stress (Arabbeigi et al, ; Hazzouri et al, ; Kiani, Arzani, & Habibi, ; Rezaei et al, ). The effects of the salinity stress on the leaf and root ionic contents also showed that the K concentration and K/Na ratio were significantly decreased under salinity conditions (Table ).…”

“…Therefore, maintenance a high potassium (K) but a low sodium (Na) in the cell cytosol, the synchronized long‐distance transport of Na in the phloem and xylem (Arzani & Ashraf, ) and the Na pumping capacity of root cells across the plasma membrane and then out of the cytosol (Chen et al, ) are the key elements in the salinity tolerance in plants. The significantly higher K/Na ratio observed in the salinity‐tolerant genotypes, as compared to the sensitive ones, is parallel to those reported previously in barley (Hazzouri et al, ; Zhu, Zhou, Shabala, & Shabala, ) and other grasses (Rezaei et al, ). In barley, Zhu et al () noted that better potassium (K) retention along with a reduced cytosol concentration of sodium (Na) in the cells enable optimal K/Na homeostasis in the cytosol which leads to a normal cellular metabolism even under salinity stress.…”

“…Our results also showed that salinity tolerance criteria, biomass/shoot dry matter and survival rate could be effective in screening the salinity‐tolerant genotypes in both cultivated and wild barley. On the other hand, under high salt concentrations, survivability is a more important selection criterion of salinity tolerance, particularly in grass species (Arabbeigi et al, ; Munns & James, ; Rezaei, Arzani, Saeidi, & Karami, ). In this study, the strong correlations between the survivability criterion and the shoot dry matter and plant height under the 300 mM NaCl showed the sustainability of the biomass production during the vegetative stage which determines how long plant lives; thus, it shows how much carbon plant can store and how large plants would become (Irving, ).…”

“…Vysotskaya et al () tested the response of two contrasting genotypes (sensitive and tolerant) of H. spontaneum to mild salinity stress and found a non‐significant genotypic difference in shoot RWC. The literature demonstrates both productive and non‐productive roles of leaf water status in different plant species including grasses (Rezaei et al, ). It is difficult to explain the discrepancies between these studies, and it is likely that several factors (e.g., differences in duration of exposure, different NaCl concentrations, or the presence of various confounding factors, such as plant growing stage, plant species, and environmental conditions) may be involved (Munns & Tester, ; Rezaei et al, ; Vysotskaya et al, ; Xu, Sibicky, & Huang, ).…”

Genetic Analysis of Flooding Tolerance in an Andean Diversity Panel of Dry Bean (Phaseolus vulgaris L.)

“…Traits associated with survivability have proved useful in the identification of the most tolerant genotypes to different abiotic stresses, such as salinity (Rezaei et al, 2017 ). Therefore, a weighted selection index was developed in which a 2-folds higher weight was assigned to the survival score.…”