Abstract
This work deals with the assessment of physiological and biochemical responses to salt stress, as well as the regulation of the expression of the K+/Na+ transporter gene-TaHKT1;5 of two Triticum aestivum L. genotypes with contrasting tolerance. According to the observations, salinity stress caused lipid peroxidation; accumulation of soluble sugars and proline; decreased osmotic potential, Fv/Fm value, and K+/Na+ ratio; and increased the activity of antioxidant enzymes in both genotypes. In the salt-tolerant genotype, the activity of enzymes, the amounts of soluble sugars and proline were higher, the osmotic potential and the lipid peroxidation were lower than in the sensitive one, and the Fv/Fm value remained unchanged. A comparison of the accumulation of Na+ and K+ ions in the roots and leaves showed that the Na+ content in the leaves is lower. The selective transport of K+ ions from roots to leaves was more efficient in the salt-tolerant genotype Mirbashir-128; consequently, the K+/Na+ ratio in the leaves and roots of this genotype was higher compared with the sensitive Fatima genotype. The semi-quantitative RT-PCR expression experiments on TaHKT1;5 indicated that this gene was not expressed in the leaf of the wheat genotypes. Under salt stress, the expression level of the TaHKT1;5 gene increased in the root tissues of the salt-sensitive genotype, while it decreased in the salt-tolerant wheat genotype. The results obtained suggest that the ion status and salt tolerance of the wheat genotypes are related to the TaHKT1;5 gene activity.
Highlights
IntroductionThe annual increase in the area of saline soils due to secondary salinization processes leads to degradation and desertification of agricultural lands, resulting in their withdrawal from circulation
Soil salinity is a serious ecological problem for many countries around the world
CAT and ascorbate peroxidase (APX) are key enzymes for the detoxification of reactive oxygen species (ROS) in the cell. These enzymes, especially APX, perform the conversion of H2O2 to water in the cell cytosol, mitochondria, and peroxisomes, as well as in the apoplastic space
Summary
The annual increase in the area of saline soils due to secondary salinization processes leads to degradation and desertification of agricultural lands, resulting in their withdrawal from circulation These processes, in turn, lead to losses in world agricultural production. Many mechanisms have been developed to minimize radial and long-distance Na+ transport in salt-tolerant plants and to prevent their accumulation at toxic levels in metabolically active tissues. These mechanisms include minimizing the input of Na+ ions as a result of selective assimilation of ions by root cells, returning Na+ ions from roots to the rhizosphere, preventing xylem from being loaded with Na+ ions, removing Na+ ions from the transpiration flux, etc. Ion channels, and signal molecules are directly involved in maintaining this ratio at optimal levels [6,7]
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