Abstract
NAC (NAM, ATAF, and CUC) transcription factors are important regulator in abiotic stress and plant development. However, knowledge concerning the functions of plant NAC TFs functioning in stress tolerance and the underlying molecular basis are still limited. In this study, we report functional characterization of the NAC TF, PbeNAC1, isolated from Pyrus betulifolia. PbeNAC1 were greatly induced by cold and drought, while salt stress had little effect on expression. PbeNAC1 was localized in the nuclei showed transactivation activity. Overexpression of PbeNAC1 conferred enhanced tolerance to multiple stresses, including cold and drought, as supported by lower levels of reactive oxygen species, higher survival rate, higher activities of enzymes, relative to wild-type (WT). In addition, steady-state mRNA levels of 15 stress-responsive genes coding for either functional or regulatory proteins were higher levels in the transgenic plants relative to the WT with drought or cold treatment. yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays showed that PbeNAC1 protein can physically interact with PbeDREB1 and PbeDREB2A. Taken together, these results demonstrate that pear PbeNAC1 plays an important role in improving stress tolerance, possibly by interacting with PbeDREB1 and PbeDREB2A to enhance the mRNA levels of some stress-associated genes.
Highlights
Plant growth and development are frequently threatened by environmental stresses such as drought and low temperature
We report that overexpression of P. betulifolia NAC1 led to enhanced cold and drought tolerance in transgenic lines
We demonstrate here that over-expression of PbeNAC1 in tobacco result in clear increase of drought and cold tolerance, which acts as a positive regulator of some stress-responsive genes expression from tobacco
Summary
Plant growth and development are frequently threatened by environmental stresses such as drought and low temperature. To cope with these stresses, plants evolved a set of physiological and molecular defense mechanisms to adapt to adverse conditions (Shinozaki and YamaguchiShinozaki, 2000). Stress-responsive genes are generally classified into two main groups based on their products, effector molecules or regulator molecules (Huang et al, 2010). Genes in the former group encode regulatory proteins, including protein kinases, phosphatases, and transcription factors (TFs), which are responsible for transducing stress signaling and regulating expression of stress-responsive genes (Shinozaki and Yamaguchi-Shinozaki, 2000). TFs are known as master regulators that plays key roles in various biological processes, so exploitation and elucidation of stressassociated TFs and their target genes will help understand key regulons and provide valuable genes for stress tolerance improvement via genetic engineering
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