| Wheat is one of the most important food crops in the world. A variety of abiotic stresses, such as drought, cold and salinity continuously pose negative impacts on growth, development and productivity. It is one of the important research topics that the regulation mechanism of plants to deal with the various environmental stresses.Abscisic acid(ABA) regulates the various plant physiological processes, especially participates in the plant responses to abiotic stresses as stress phytohormone. 9-cis-epoxycarotenoid dioxygenase(NCED) is a key enzyme in ABA biosynthesis pathway. Here, a NCED gene, designated TaNCED3 was isolated from the leaves of wheat. The TaNCED3 had a 1,887-bp ORF, which encoded a peptide of 628 amino acids. At the N-terminus of the TaNCED3 protein located a chloroplast transit peptide sequence. The TaNCED3 protein shared high identity with other NCEDs from different species by multiple sequence alignments. Quantitative real-time PCR analysis showed that the expression of TaNCED3 was strongly up-regulated by adding exogenous mannitol and ABA, but not induced by salt and cold stress. Over-expression of the TaNCED3 gene in Arabidopsis resulted in a higher ABA level under both normal growth conditions and drought stress.We also detected lower relative water loss, higher free proline content and stomatal conductance in transgenic plants than WT. In addition, transgenic plants displayed enhanced tolerance to drought stress and delayed seed germination. These results indicated that TaNCED3 played a primary role in the regulation of drought stress and seed germination. |
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