Effect of salt stress on the expression of genes of K+/Na+-transporters HKT, SOD and Nfn in Triticum durum and Triticum aestivum
The problem of determining the potential of salt tolerance of wheat is one of the most pressing in the selection practice for areas with primary and secondary salinity. One of the ways to overcome the negative impact of the salinity factor is the use of saline-tolerant breeding lines and wheat genotypes. A high concentration of mineral salts has a negative effect mainly due to the violation of the ionic and osmotic equilibrium of the cell. In saline soils, high levels of sodium ions lead to inhibition of plant growth and even death. Plants have several mechanisms of protection against the harmful effects of salts, which include the removal of toxic Na+ and Cl- ions, blocking the transport of Na+ ions into the cell, the exclusion of Na+ from the transpiration stream, and other mechanisms. Expression of K+/Na+-transporter genes HKT is important for characterizing the salt tolerance of wheat. In genotypes of durum and aestivum wheat Orenburgskaya 10 and Orenburgskaya 22 under salt stress, an increase in the expression of the K+/Na+ genes of transporters of the HKT 1 and HKT 2 families is observed by 3-4 times. The expression level of superoxidedismutase SOD and bifunctional enzyme catalyzing reduction of nicotinamide adenine dinucleotide phosphate Nfn increases by 2-4 times, which indicates the high adaptive properties of these wheat genotypes to salt stress. Probably, the expression of the HKT, SOD and Nfn genes are interconnected. An increase in the level of expression of the NKT, SOD and Nfn families in roots and leaves under salt stress conditions are associated with the rapid recovery of the K+/Na+ ion balance and the removal of toxic Na+ and ions of reactive oxygen forms, i. e. protective function. It was noted that with prolonged exposure to salinity, the plant adapts to such extreme conditions and the role of ion transporters decreases: the level of expression of transporters НКТ 1;4 decreases, wheat is more resistant to chloride salinity. Thus, it was found that the varieties of wheat Orenburgskaya 10 and Orenburgskaya 22 have different resistance to prolonged exposure of sodium chloride.