The Brachypodium distachyon BdWRKY36 gene confers tolerance to drought stress in transgenic tobacco plants

Abstract

The expression of BdWRKY36 was upregulated by drought treatment. BdWRKY36 -overexpressing transgenic tobacco increased drought tolerance by controlling ROS homeostasis and regulating transcription of stress related genes. WRKY transcription factor plays important roles in plant growth, development and stress response. However, the function of group IIe WRKYs is less known. In this study, we cloned and characterized a gene of group IIe WRKY, designated as BdWRKY36, from Brachypodium distachyon. Transient expression of BdWRKY36 in onion epidermal cell suggested its localization in the nucleus. Transactivation assay revealed that the C-terminal region, instead of full length BdWRKY36, had transcriptional activity. BdWRKY36 expression was upregulated by drought. Overexpression of BdWRKY36 in transgenic tobacco plants resulted in enhanced tolerance to drought stress. Physiological-biochemical indices analyses showed that BdWRKY36-overexpressing tobacco lines had lesser ion leakage (IL) and reactive oxygen species (ROS) accumulation, but higher contents of chlorophyll, relative water content (RWC) and activities of antioxidant enzyme than that in control plants under drought condition. Meanwhile expression levels of some ROS-scavenging and stress-responsive genes were upregulated in BdWRKY36-overexpressing tobacco lines under drought stress. These results demonstrate that BdWRKY36 functions as a positive regulator of drought stress response by controlling ROS homeostasis and regulating transcription of stress related genes.

Genome-wide survey of heat shock factors and heat shock protein 70s and their regulatory network under abiotic stresses in Brachypodium distachyon

“…Results showed that BdCBF1 was up-regulated rapidly after cold treatment, while BdCBF2 showed an obviously increased expression under salt and drought stresses, which was consistent with previous studies on BdCBF gene functional characterization [73]. BdWRKY36 expression was up-regulated by cold and drought stresses, similar results were reported in previous paper [74]. APXs were the key enzymes in a major hydrogen peroxide-detoxifying system in plant, which was also called ascorbate-glutathione cycle [75].…”

Isolation and characterization of MbWRKY2 gene involved in enhanced drought tolerance in transgenic tobacco

“…These results above suggest that overexpression of MbWRKY2 in transgenic tobaccos results in the higher levels of ROSscavenging genes/enzymes. The results above were similar to the overexpression of BdWRKY36 in tobaccos (Sun et al 2015). Furthermore, the expression levels of AtRD29A and AtNCED3 were regarded as indicators for drought stress, which were more higher in VlWRKY48-overexpressing Arabidopsis than WT line when dealt with drought stress (Zhao et al 2018).…”

“…Some other WRKY TFs were reported to localize also in the nucleus (Ramamoorthy et al 2008;Liu et al 2014;Wang et al 2016). The chlorophyl content and RWC were usually used as the markers for drought stress degree, which in BdWRKY36-overexpressing tobaccos were more higher than those in WT line under drought stress (Sun et al 2015). Proline, which has been associated with the general stress response, may also be cryoprotective, since proline overproducers display an enhanced drought tolerance (Toka et al 2010).…”

TaWRKY51 promotes lateral root formation through negative regulation of ethylene biosynthesis in wheat (Triticum aestivum L.)

“…The WRKY TFs show high binding affinity to the W-box sequence (T/C)TGAC(C/T) (Rushton et al, 2010). The WRKY TFs are known to play critical roles in biotic and abiotic stress responses, such as pathogen infection (Liu et al, 2005;Mao et al, 2011;Chen et al, 2013;Dey et al, 2014), high salt (Niu et al, 2012;Liang et al, 2017), drought stress (Luo et al, 2013;Sun et al, 2015;Li et al, 2017), oxidative stress , nutrient stress (Chen et al, 2009;Su et al, 2015;Dai et al, 2016) and high temperature (Cai et al, 2015;He et al, 2016). In addition to their important role in stress responses, WRKYs are also involved in a wide range of plant growth and development processes, such as seed dormancy and germination (Luo et al, 2005;Zhang et al, 2011;Ding et al, 2014), seed size (Gu et al, 2017), fruit maturation (Cheng et al, 2016;Ye et al, 2017) and senescence (Besseau et al, 2012;Meng et al, 2013).…”