Abstract:

Plant high-affinity potassium transporter （HKT） genes encode K⁺ or Na⁺ transport or K⁺-Na⁺ co-transport plasma membrane channel proteins， which play an important role in the process of plant stress resistance. This research investigated the function of EeHKT1；4 in Elytrigia elongata （GenBank： KF956112.1）. An EeHKT1；4 overexpression plant expression vector was constructed and transformed into Arabidopsis thaliana， and the drought and salt tolerance of transgenic Arabidopsis plants were evaluated and analyzed. No difference was found in the primary root length between wild-type （WT） and transgenic lines under normal growth conditions， but NaCl and mannitol treatments inhibited the growth of WT and transgenic plant roots， and inhibited the root length of transgenic lines more than the root length of WT under the same drought and salt treatment conditions. There was no significant difference between WT and transgenic lines under normal growth conditions， but under NaCl and mannitol treatment， WT showed leaf atrophy and yellowing， while only some plants in transgenic lines showed leaf atrophy， and the survival rate of transgenic lines was higher than WT under the same stress conditions. Nitroblue tetrazolium and diaminobenzidine staining results showed that the leaf staining in WT and transgenic lines was relatively weak under normal growth conditions， and the intensity of staining in all leaves gradually deepened with increase in NaCl and mannitol concentration. Also， the intensity of staining in the WT was higher than transgenic lines under the same stress. With the expression level under normal growth conditions as the control， AtSOS1 gene were incrementally up-regulated in WT and transgenic plants with increase in NaCl concentration， and the expression levels in the transgenic plants were higher than that in WT. The expression of the gene AtNHX1 was up-regulated under NaCl treatment and the expression level in transgenic plants was lower than in the WT. Except for a transgenic line ‘L5’， no change in AtNHX1 gene expression associated with increase in NaCl concentration was detected in WT or transgenic lines. The genes AtRD29B and AtP5CS1 were both up-regulated under mannitol treatment， and their expression levels in transgenic plants were higher than in WT plants. In summary， EeHKT1；4 overexpression reduced the accumulation of superoxide anion and H₂O₂ in A. thaliana under adversity stress， induced the up-regulated expression of stress-resistant genes， and enhanced the drought and salt tolerance of A. thaliana.

Key words: Elytrigia elongata, EeHKT1, 4, transgenic, diaminobenzidine staining, nitroblue tetrazoliun staining