Effect of zinc nutrition on salinity-induced oxidative damages in wheat genotypes differing in zinc deficiency tolerance

Zinc deficiency and salinity are well-documented soil problems and often occur simultaneously in cultivated soils. Usually, plants respond to environmental stress factors by activating their antioxidative defense mechanisms. The antioxidative response of wheat genotypes to salinity in relation to Zn nutrition is not well understood. So, we investigated the effect of Zn nutrition on the growth, membrane permeability and sulfhydryl group (–SH groups) content of root cells and antioxidative defense mechanisms of wheat plants exposed to salt stress. In a hydroponic experiment, three bread wheat genotypes (Triticum aestivum L. cvs. Rushan, Kavir, and Cross) with different Zn-deficiency tolerance were exposed to adequate (1 μM Zn) and deficient (no Zn) Zn supply and three salinity levels (0, 60, and 120 mM NaCl). The results obtained showed that adequate Zn nutrition counteracted the detrimental effect of 60 mM NaCl level on the growth of all three wheat genotypes while it had no effect on the root and shoot growth of ‘Rushan’ and ‘Kavir’ at the 120 mM NaCl treatment. At the 0 and 60 mM NaCl treatments, Zn application decreased root membrane permeability while increased –SH group content and root activity of catalase (CAT) and superoxide dismutase (SOD) in ‘Rushan’ and ‘Kavir’. In contrast, Zn had no effect on the root membrane permeability and –SH group content of ‘Rushan’ and ‘Kavir’ exposed to the 120 mM NaCl treatment. At all salinity levels, ‘Cross’ plants supplied with Zn had lower root membrane permeability and higher –SH group content compared to those grown under Zn-deficient conditions. At the 0 and 60 salinity levels, Zn-deficient roots of Kavir and Rushan genotype leaked significantly higher amounts of Fe and K than the Zn-sufficient roots. In contrast, at the 120 mM treatment, Zn application had no effect or slightly increased Fe and K concentration in the root ion leakage of these wheat genotypes. For ‘Cross’, at all salinity levels, Zn-deficient roots leaked significantly higher amounts of Fe and K compared with the Zn-sufficient roots. The differential tolerance to salt stress among wheat genotypes examined in this study was related to their tolerance to Zn-deficiency, –SH group content, and root activity of CAT and SOD. Greater tolerance to salinity of Zn-deficiency tolerant genotype ‘Cross’ is probably associated with its greater antioxidative defense capacity

Unravelling salt stress in plants through proteomics

Plants like other organisms are mostly under the threat of various stresses (both biotic as well as abiotic). Being sessile, plants lack the mechanisms to flee from these unfavourable situations. The development of exclusive and complicated responses to these environmental stresses in plants has fostered through evolution. Such alterations can influence plant growth, production and productivity in agriculture, plant nutritional potential and metabolic profile. Hence, plant abiotic stress has always been a matter of concern for the world economy and maintenance of human life on earth. Salinity stress, being one of the main abiotic stresses, may bring the morphological, anatomical, and physiological changes in plants. Distributed in both irrigated and non-irrigated areas of the world, around 6% of the world’s total land area is affected by salt stress. So, it is a major concern to adopt the strategies against this great challenge by unravelling the mechanisms to overcome salt stress. In order to meet the challenges for biotechnological improvement of crop productivity; various steps involving genes, transcripts, proteins and metabolites, controlling the stress resistance and/or architecture of crop plants in a wide array of environments needed to be recognized. Proteomics, the protein complement of genome, these days is one of the leading branches of research which enables the large-scale ­scanning of various substances, and offers great potential for post-genomics to elucidate the genotype-phenotype connections. The present chapter is an account of current knowledge in this regard. It focuses on effects of salt stress unrevealed by proteomics tools. It comprises information on recent advances in proteomics, which could be a new opportunity to comprehend abiotic responses and categorize genes responsible for significant crop traits