Heterologous Expression of MfWRKY7 of Resurrection Plant Myrothamnus flabellifolia Enhances Salt and Drought Tolerance in Arabidopsis

Abstract

Drought and salinity have become major environmental problems that affect the production of agriculture, forestry and horticulture. The identification of stress-tolerant genes from plants adaptive to harsh environments might be a feasible strategy for plant genetic improvement to address the challenges brought by global climate changes. In this study, a dehydration-upregulated gene MfWRKY7 of resurrection Plant Myrothamnus flabellifolia, encoding a group IId WRKY transcription factor, was cloned and characterized. The overexpression of MfWRKY7 in Arabidopsis increased root length and tolerance to drought and NaCl at both seedling and adult stages. Further investigation indicated that MfWRKY7 transgenic plants had higher contents of chlorophyll, proline, soluble protein, and soluble sugar but a lower water loss rate and malondialdehyde content compared with wild-type plants under both drought and salinity stresses. Moreover, the higher activities of antioxidant enzymes and lower accumulation of O2− and H2O2 in MfWRKY7 transgenic plants were also found, indicating enhanced antioxidation capacity by MfWRKY7. These findings showed that MfWRKY7 may function in positive regulation of responses to drought and salinity stresses, and therefore, it has potential application value in genetic improvement of plant tolerance to abiotic stress.

Overexpression of a WRKY transcription factor McWRKY57-like from Mentha canadensis L. enhances drought tolerance in transgenic Arabidopsis

“…In addition, a series of antioxidant systems, including SOD, CAT, and POD, have been evolved in plants to mitigate ROS-induced damages. A growing number of studies have demonstrated that WRKYs enhance drought tolerance by reducing MDA content or increasing antioxidant enzyme activity in transgenic plants [39,43,50]. Our data show that MDA content is signi cantly decreased, and SOD, CAT, and POD activities are evidently enhanced in McWRKY57-like OE plants after drought treatment (Fig.…”

“…Similarly, we found that McWRKY57-like plays a positive role in McWRKY57-likeoverexpressing transgenic Arabidopsis plants. The size and architecture of the root system are key factors affecting the ability of plants to access water and nutrients, and root length is an important indicator of plant drought tolerance [42][43][44]. We found that, although the root growth of WT and McWRKY57-like OE transgenic seedlings is not signi cantly different, under drought conditions, the root length is signi cantly longer in McWRKY57-like OE transgenic seedlings than in WT seedlings (Fig.…”

“…Among them, proline not only acts as an osmolyte but also functions as a potent antioxidant and programmed cell death inhibitor, making it one of the most important indicators of plant drought tolerance [47,48]. Soluble sugars and soluble proteins are also important osmoregulatory substances that maintain turgor pressure and macromolecular structure and function, thereby improving plant drought tolerance [43,44]. In this study, osmotic stresses signi cantly enhance McWRKY57-like expression, and the contents of these three osmolytes are markedly increased in McWRKY57-like OE plants under drought treatment (Figs.…”

Overexpression of a WRKY transcription factor McWRKY57-like from Mentha canadensis L. enhances drought tolerance in transgenic Arabidopsis

“…Among them, proline not only acts as an osmolyte but also functions as a potent antioxidant and programmed cell death inhibitor, making it one of the most important indicators of plant drought tolerance [ 47 , 48 ]. Soluble sugars and soluble proteins are also important osmoregulatory substances that maintain turgor pressure and macromolecular structure and function, thereby improving plant drought tolerance [ 43 , 44 ]. In this study, osmotic stresses significantly enhance McWRKY57-like expression, and the contents of these three osmolytes are more markedly increased in McWRKY57-like OE plants than in WT under drought treatment (Figs.…”

“…In addition, a series of antioxidant systems, including SOD, CAT, and POD, have been evolved in plants to mitigate ROS-induced damages. A growing number of studies have demonstrated that WRKYs enhance drought tolerance by reducing MDA content or increasing antioxidant enzyme activity in transgenic plants [ 39 , 43 , 50 ]. Our data show that MDA content is significantly decreased, and SOD, CAT, and POD activities are evidently enhanced in McWRKY57-like OE plants compared with WT plants after drought treatment (Fig.…”