Abstract
Environmental stresses frequently affect plant growth and development, and many genes have been found to be induced by unfavorable environmental conditions. Here, we reported the biological functions of TaNAC2D, a stress-related NAC (NAM, ATAF, and CUC) gene from wheat. TaNAC2D showed transcriptional activator activity in yeast. TaNAC2D-GFP fusion protein was localized in the nucleus of wheat mesophyll protoplasts. TaNAC2D transcript abundance was significantly induced by NaCl, PEG6000, and abscisic acid (ABA) at seedling stage, and repressed by NaCl and PEG6000 at mature plant stage. When TaNAC2D was introduced into Arabidopsis, the 35-day-old soil-grown TaNAC2D-overexpression (TaNAC2D-OX) plants displayed slower stomatal closure, higher water loss rate, and more sensitivity to salt and drought stresses compared with WT plants. In contrast, TaNAC2D-OX seedlings, grown on 1/2 MS medium supplemented with different concentrations of NaCl, Mannitol, and MV, had enhanced tolerances to salt, osmotic and oxidative stresses during seed germination and post-germination periods. The opposite stress-responsive phenotypes of transgenic Arabidopsis were consistent with the expression patterns of TaNAC2D in wheat. Moreover, under high salinity and dehydration conditions, three marker genes, including NCED3, RD29A, and RD29B, were down-regulated in 35-day-old TaNAC2D-OX plants grown in soil and up-regulated in 14-day-old TaNAC2D-OX seedlings grown on 1/2 MS medium. Our results suggest that the change in growth stages and environmental conditions may regulate TaNAC2D’s function.
Highlights
Environmental stresses may adversely affect plant development and yield
Sequence alignment and phylogenetic analyses (Supplementary Figures S1A and S2) revealed that TaNAC2D was highly homologous to HvSNAC1 (GenBank: AEG21060.1), OsSNAC1(GenBank: AIX03022.1), and almost identical to TaNAC2 (AAU08786.1), indicating that TaNAC2D, like these three NAC genes (Hu et al, 2006; Mao et al, 2012; Al Abdallat et al, 2014), participated in plant stress responses
TaNAC2D-GFP fusion protein and DAPI were detected only in the nucleus of wheat mesophyll protoplasts (Figure 1B). These results indicate that TaNAC2D may function as a transcription factor
Summary
Environmental stresses may adversely affect plant development and yield. To protect plant against environmental stresses, many genes have been induced, and the products of these stressinducible genes may provide a protection from stress damage. Stress-inducible genes are largely regulated by transcription factors (TFs). Transgenic plants overexpressing TF genes often show enhanced stress tolerance. Overexpression of TaASR1 in Nicotiana tabacum displays improved tolerance to dehydration and oxidative stresses (Hu et al, 2013). Arabidopsis plants overexpressing GsWRKY20 result in decreased water loss and increased drought tolerance (Luo et al, 2013). In rice (Oryza sativa), overexpression of OsMYB2 exhibits enhanced stress tolerance and increased sensitivity to exogenous ABA (Yang et al, 2012)
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