Abstract
ABSTRACTPlant-specific WRKY transcription factors are widely involved in abiotic stress responses. In this study, a WRKY gene was isolated from Malus baccata (L.) Borkh and designated it as MbWRKY2. Subcellular localization showed that MbWRKY2 was localized in the nucleus. The expression levels of MbWRKY2 were up-regulated by abiotic stresses in M. baccata. When MbWRKY2 was introduced into tobacco, it improved drought stress tolerance in transgenic plants. The transgenic tobaccos had the higher contents of chlorophyl, proline, relative water content, AsA, and GSH, increased activities of CAT, APX, SOD, and POD, and decreased levels of MDA, H2O2, and electrolyte leakage than wild-type, especially when dealt with dehydration treatment. Moreover, the MbWRKY2-OE plants enhanced the expression of oxidative stress response and stress-related genes involved in osmotic adjustment and membrane protection. These results suggest that MbWRKY2 gene plays a positive regulatory role in drought stress response.
Highlights
As sessile organisms, plants are frequently exposed to variable environmental stresses, such as drought, salt, heat, chilling, pathogen attack, and nutrient deprivation, which adversely affect plant growth, development, and productivity (Gong & Liu 2013)
To investigate the evolutionary relationship among plant WRKY transcription factors (TFs), 9 proteins of WRKY TFs from different species were analyzed by DNAMAN (v.6.0)
All the WRKY TFs include a WRKY domain (WRKYGQK) and one conserved C2H2 or C2HC zinc-finger motif (Liu et al 2014). These results showed that the WRKY TFs family was highly conserved during evolution
Summary
Plants are frequently exposed to variable environmental stresses, such as drought, salt, heat, chilling, pathogen attack, and nutrient deprivation, which adversely affect plant growth, development, and productivity (Gong & Liu 2013). Environmental stresses are perceived and transduced through a chain of signaling molecules that affect regulatory element of stress-inducible genes to initiate the synthesis of different classes of protein including transcription factors (TFs), enzymes, molecular chaperons, ion channels, and transporters or alter their activities (Mukhopadhyay et al 2004). To avoid such deficiencies, plants have developed adaptable mechanisms to perceive external signaling networks and to manifest adaptive responses with appropriate physiological, cellular, and molecular changes (Liu et al 2014). These studies mostly focused on model plants or crops, and the roles of the WRKY genes in Malus plant stress responses were less well known
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