Abstract:

Salt stress can trigger several physiological responses in plants such as increased accumulation of ABA and antioxidant enzyme activities, which have been closely associated with the tolerance of plants to salt stress. In the present study a novel zeaxanthin epoxidase gene, designated EsABA1, was isolated from Eutrema salsugineum. EsABA1 contained a full-length open reading frame (ORF) of 2001 bp, encoding 666 amino acids. Transcription of EsABA1 rapidly accumulated after exposure to various abiotic stresses, suggesting that the EsABA1 gene was involved in multiple stress responses and tolerance. To further investigate the roles of EsABA1 under salt-stress conditions, transgenic tobacco lines that ectopically overexpressed EsABA1 were obtained. These transgenic lines exhibited more tolerance to salt stress than wild-type (WT) plants, and overexpression of EsABA1 increased the contents of ABA and proline as compared to WT plants under salt-stress conditions. Moreover, the expression levels of stress responsive genes and activities of antioxidant enzymes were much higher in the EsABA1-overexpressing lines than in WT plants. Therefore, our findings indicated that the elevated expression of EsABA1 enhanced the tolerance of transgenic tobacco plants to high salinity stress.

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