Huiming Gao, Yafei Wang, Ping Xu and Zhengbin Zhang
Frontier Plant. Sci. 7 August 2018
Drought is a major environmental stress that severely restricts plant growth and crop productivity. A previous study showed that TaWRKY2 from wheat (Triticum aestivum) plays an important role in drought stress tolerance. In the present study, we isolated the promoter of TaWRKY2 and identified multiple regulatory cis-elements in the promoter region. The activity of the TaWRKY2 promoter was induced by drought, salt, heat, and abscisic acid (ABA). We also generated TaWRKY2-overexpressing transgenic wheat, and found that the transgenic seedlings exhibited significantly enhanced tolerance to drought stress, as evidenced by a higher survival rate and lower water loss rate of detached leaves compared with wild type (WT) plants. In addition, the transgenic lines had higher contents of free proline, soluble sugar, and chlorophyll. During a prolonged period of drought stress before the heading stage, the growth of WT plants was inhibited, whereas the TaWRKY2-overexpressing lines progressed to the heading stage. The increased grain yield of the transgenic wheat lines reflected the cumulative effects of longer panicle length, more kernels per spike, and greater aboveground biomass. Our findings show that TaWRKY2 can enhance drought tolerance and increase grain yield in wheat, thus providing a promising candidate target for improving the drought tolerance of wheat cultivars through genetic engineering.
See: https://www.frontiersin.org/articles/10.3389/fpls.2018.00997/full
Figure 1: Promoter cloning and analysis of TaWRKY2. (A) The 2,166-bp promoter upstream of the ATG start codon of TaWRKY2. (B) Analysis of the cis-regulatory promoter elements. (C) Responsiveness of the promoter to the following abiotic stresses: (a) control, (b) drought (20% polyethylene glycol for 24 h), (c) salt (300 mM NaCl for 24 h), (d) heat (37°C for 12 h), (e) cold (4°C for 12 h), (f) sprayed with H2O for 24 h, and (g) sprayed with ABA (200 mM for 24 h).
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