Linking osmotic adjustment and stomatal characteristics with salinity stress tolerance in contrasting barley accessions

Salinity tolerance is a complex trait – both physiologically and genetically – and the issue of which mechanism or trait has bigger contribution towards the overall plant performance is still hotly discussed in the literature. In this work, a broad range of barley (Hordeum vulgare L. and Hordeum spontaneum L.) genotypes contrasting in salinity stress tolerance were used to investigate the causal link between plant stomatal characteristics, tissue ion relations, and salinity tolerance. In total, 46 genotypes (including two wild barleys) were grown under glasshouse conditions and exposed to moderate salinity stress (200mM NaCl) for 5 weeks. The overall salinity tolerance correlated positively with stomata density, leaf K+ concentration and the relative contribution of inorganic ions towards osmotic adjustment in the shoot. At the same time, no correlation between salinity tolerance and stomatal conductance or leaf Na+ content in the shoot was found. Taken together, these results indicate the importance of increasing stomata density as an adaptive tool to optimise efficiency of CO2 assimilation under moderate saline conditions, as well as benefits of the predominant use of inorganic osmolytes for osmotic adjustment in barley. Another finding of note was that wild barleys showed rather different strategies dealing with salinity, as compared with cultivated varieties.

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Plant ionic relation and whole-plant physiological responses to waterlogging, salinity and their combination in barley

Functional Plant Biology ◽

10.1071/fp16385 ◽

2017 ◽

Vol 44 (9) ◽

pp. 941 ◽

Cited By ~ 8

Author(s):

Zhinous Falakboland ◽

Meixue Zhou ◽

Fanrong Zeng ◽

Ali Kiani-Pouya ◽

Lana Shabala ◽

...

Keyword(s):

Stress Tolerance ◽

Salinity Stress ◽

Molecular Mechanisms ◽

Photochemical Efficiency ◽

Damage Index ◽

Nacl Stress ◽

Plant Performance ◽

Combined Stress ◽

Salinity Stress Tolerance ◽

Stress Damage

Waterlogging and salinity stresses significantly affect crop growth and global food production, and these stresses are often interrelated because waterlogging can lead to land salinisation by transporting salts to the surface. Although the physiological and molecular mechanisms of plant responses to each of these environmental constraints have been studied in detail, fewer studies have dealt with potential mechanisms underlying plant tolerance to the combined stress. This gap in knowledge is jeopardising the success of breeding programs. In the present work we studied the physiological and agronomical responses of 12 barley varieties contrasting in salinity stress tolerance to waterlogging (WL), salinity (NaCl) and combined (WL/NaCl) stresses. Stress damage symptoms were much greater in plants under combined WL/NaCl stress than those under separate stresses. The shoot biomass, chlorophyll content, maximum photochemical efficiency of PSII and shoot K+ concentration were significantly reduced under WL/NaCl conditions, whereas shoot Na+ concentration increased. Plants exposed to salinity stress showed lower damage indexes compared with WL. Chlorophyll fluorescence Fv/Fm value showed the highest correlation with the stress damage index under WL/NaCl conditions (r = –0.751) compared with other measured physiological traits, so was nominated as a good parameter to rank the tolerance of varieties. Average FW was reduced to 73 ± 2, 52 ± 1 and 23 ± 2 percent of the control under NaCl, WL and combined WL/NaCl treatments respectively. Generally, the adverse effect of WL/NaCl stress was much greater in salt-sensitive varieties than in more tolerant varieties. Na+ concentrations of the shoot under control conditions were 97 ± 10 µmol g–1 DW, and increased to 1519 ± 123, 179 ± 11 and 2733 ± 248 µmol g–1 under NaCl, WL and combined WL/NaCl stresses respectively. K+ concentrations were 1378 ± 66, 1260 ± 74, 1270 ± 79 and 411 ± 92 µmol g–1 DW under control, NaCl, WL and combined WL/NaCl stresses respectively. No significant correlation was found between the overall salinity stress tolerance and amount of Na+ accumulated in plant shoots after 15 days of exposure to 250 mM NaCl stress. However, plants exposed to combined salinity and WL stress showed a negative correlation between shoot Na+ accumulation and extent of salinity damage. Overall, the reported results indicate that K+ reduction in the plants under combined WL/NaCl stress, but not stress-induced Na+ accumulation in the shoot, was the most critical feature in determining the overall plant performance under combined stress conditions.

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GABA operates upstream of H+-ATPase and improves salinity tolerance in Arabidopsis by enabling cytosolic K+ retention and Na+ exclusion

Journal of Experimental Botany ◽

10.1093/jxb/erz367 ◽

2019 ◽

Vol 70 (21) ◽

pp. 6349-6361 ◽

Cited By ~ 17

Author(s):

Nana Su ◽

Qi Wu ◽

Jiahui Chen ◽

Lana Shabala ◽

Axel Mithöfer ◽

...

Keyword(s):

Stress Tolerance ◽

Salinity Stress ◽

Salinity Tolerance ◽

Plant Roots ◽

Transcript Levels ◽

Root Epidermis ◽

Beneficial Effects ◽

Salinity Stress Tolerance ◽

Increased Activity

GABA has beneficial effects on salinity stress tolerance in Arabidopsis linked to increased activity of H+-ATPase, reduced ROS-induced K+ efflux from root epidermis, and increased SOS1 and NHX1 transcript levels in plant roots.

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Genome-Wide Association Mapping of Salinity Tolerance at the Seedling Stage in a Panel of Vietnamese Landraces Reveals New Valuable QTLs for Salinity Stress Tolerance Breeding in Rice

Plants ◽

10.3390/plants10061088 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1088

Author(s):

Thao Duc Le ◽

Floran Gathignol ◽

Huong Thi Vu ◽

Khanh Le Nguyen ◽

Linh Hien Tran ◽

...

Keyword(s):

Stress Tolerance ◽

Salinity Stress ◽

Salinity Tolerance ◽

Seedling Stage ◽

Genome Wide Association ◽

Transport Systems ◽

Breeding Programs ◽

Genome Wide ◽

A Genome ◽

Salinity Stress Tolerance

Rice tolerance to salinity stress involves diverse and complementary mechanisms, such as the regulation of genome expression, activation of specific ion-transport systems to manage excess sodium at the cell or plant level, and anatomical changes that avoid sodium penetration into the inner tissues of the plant. These complementary mechanisms can act synergistically to improve salinity tolerance in the plant, which is then interesting in breeding programs to pyramidize complementary QTLs (quantitative trait loci), to improve salinity stress tolerance of the plant at different developmental stages and in different environments. This approach presupposes the identification of salinity tolerance QTLs associated with different mechanisms involved in salinity tolerance, which requires the greatest possible genetic diversity to be explored. To contribute to this goal, we screened an original panel of 179 Vietnamese rice landraces genotyped with 21,623 SNP markers for salinity stress tolerance under 100 mM NaCl treatment, at the seedling stage, with the aim of identifying new QTLs involved in the salinity stress tolerance via a genome-wide association study (GWAS). Nine salinity tolerance-related traits, including the salt injury score, chlorophyll and water content, and K+ and Na+ contents were measured in leaves. GWAS analysis allowed the identification of 26 QTLs. Interestingly, ten of them were associated with several different traits, which indicates that these QTLs act pleiotropically to control the different levels of plant responses to salinity stress. Twenty-one identified QTLs colocalized with known QTLs. Several genes within these QTLs have functions related to salinity stress tolerance and are mainly involved in gene regulation, signal transduction or hormone signaling. Our study provides promising QTLs for breeding programs to enhance salinity tolerance and identifies candidate genes that should be further functionally studied to better understand salinity tolerance mechanisms in rice.

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