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Salt tolerant wheat landraces and Gly II transformed lines show distinct biochemical mechanisms of stress tolerance

Kaur, L., Asthir, B., Bains, N.S.
Cereal research communications 2019 v.47 no.2 pp. 264-276
Agrobacterium, Oryza sativa, Triticum, antioxidant enzymes, ascorbic acid, biochemical mechanisms, biomass, carotenoids, chlorophyll, cultivars, electrolyte leakage, enzyme activity, genes, genetically modified organisms, genotype, glutathione, glutathione-disulfide reductase, growth retardation, homeostasis, hydrogen peroxide, landraces, malondialdehyde, oxidative stress, potassium, saline soils, salt stress, salt tolerance, seedlings, sodium, sodium chloride, stress tolerance, sugar content, wheat, India
The present investigation was carried out to study the distinct salt tolerance mechanism in two sets of material, Gly II transgenics and Kharchia landraces. The Gly II transgenics were developed for glyoxalase II (osglyII) gene (GenBank accession no. AY054407) from Oryza sativa through Agrobacterium mediated method in the background of wheat cultivar PBW 621. Kharchia 65 is a salt tolerant landrace derivative developed from Kharchia local which is native to saline soils of Rajasthan. The six wheat genotypes, viz. Kharchia local, Kharchia 65, PBW 621, G-2-2, G-3-4 and G-1-13 were evaluated for growth parameters, antioxidant enzymes and contents of glutathione, ascorbic acid, malondialdehyde (MDA), H₂O₂, sugars, chlorophyll, carotenoid, electrolyte leakage (EL) and Na⁺, K⁺ under control and two salt treatments (150 mM and 250 mM NaCl). The activities of antioxidant enzymes, glutathione, sugar content increased in both GlyII and Kharchia genotypes as compared to PBW 621. The GlyII activity increased (77–84%) in GlyII genotypes alongwith content of reduced glutathione (GSH) to maintain redox homeostasis. Apparently, GlyII and Kharchia genotypes exhibited minimum oxidative stress due to low content of MDA, H₂O₂, diminished EL and thereby causing less growth reduction and maintaining high chlorophyll and carotenoid level as compared to PBW 621. In addition, Gly II transgenic material and Kharchia lines showed less Na⁺ accumulation, greater seedling biomass and sugar content due to its salt tolerance mechanism. We infer that GlyII activity enhances GSH which play significant role in detoxifying ROS to establish stress homeostasis. The route for generation of GSH is via ascorbate-glutathione pathway mediated by glutathione reductase. Hence, GlyII transgenics and Kharchia genotypes can diminish salt stress following above mechanism.