Dehydration-induced WRKY transcriptional factor MfWRKY70 of Myrothamnus flabellifolia enhanced drought and salinity tolerance in Arabidopsis

Authors: XIANG, XIANG-YING - Sichuan Agricultural University; CHEN, JIA - Sichuan Agricultural University; XU, WEN-XIN - Sichuan Agricultural University; QIU, JIA-RUI - Sichuan Agricultural University; SONG, LI - Sichuan Agricultural University; WANG, JIA-TONG - Sichuan Agricultural University; TANG, RONG - Sichuan Agricultural University; CHEN, DUOER - Sichuan Agricultural University; Jiang, Cai-Zhong; HUANG, ZHUO - Sichuan Agricultural University

Submitted to: Biomolecules EISSN 2218-273X
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2021
Publication Date: 2/22/2021
Citation: Xiang, X., Chen, J., Xu, W., Qiu, J., Song, L., Wang, J., Tang, R., Chen, D., Jiang, C., Huang, Z. 2021. Dehydration-induced WRKY transcriptional factor MfWRKY70 of Myrothamnus flabellifolia enhanced drought and salinity tolerance in Arabidopsis. Biomolecules. 11(2). Article 327. https://doi.org/10.3390/biom11020327.
DOI: https://doi.org/10.3390/biom11020327

Interpretive Summary: Plants in nature were exposed to changing environmental conditions and subjected to a variety of biotic and abiotic stresses. To increase the probability of survival, plants have to adapt to these hostile environments through evolutionary and regulatory mechanisms. As the major abiotic stresses, drought and high salinity detrimentally impact the growth, development, and productivity of plants, even cause serious loss of agricultural yield. Therefore, it is of great significance to discover the genes related to stress tolerance and the underlying molecular mechanism that are essential for the genetic improvement of plant stress tolerance and the sustainable development of human society. As the only woody resurrection plants, angiosperm Myrothamnus flabellifolia, known as homoiochlorophyllous desiccation-tolerant plants (HDTs), could rapidly reactivate after the dehydration rate of up to 95%, besides, physiological function could restore normal operation to before desiccation. Although morphological characteristics of Myrothamnus flabellifolia have been well studied, few genes of M. flabellifolia related to desiccation tolerance were characterized and the underlying molecular mechanisms remain unclear. WRKY transcription factors (WRKYs), as a large family of plant transcription factor (TF), participate in a variety of biological processes in plants including root growth, the quality of blossom clusters, senescence of leaf, fruit maturation, and resistance to pathogens. In recent years, increasing pieces of evidence proved that TFs serve as critical roles in biotic and abiotic stress signaling. Some WRKY transcription factors were particularly induced by a combination of drought and cold stress treatments or drought and heat shock stress treatments simultaneously. Thus, WRKYs are considered as a reservoir for discovery of genes related to stress tolerance. Previous transcriptome analysis of M. flabellifolia showed that MfWRKY70, a homologue to AtWRKY70 was significantly up-regulated at early dehydration stage, suggesting that it may play some roles during dehydration. In this study, the MfWRKY70 was cloned and its potential functions involved in drought and salinity tolerance were investigated in Arabidopsis. Our results indicated that MfWRKY70 was localized in the nucleus and could significantly increase tolerance to drought, osmotic, and salinity stresses by promoting root growth, water retention, as well as enhancing antioxidant enzyme system and maintaining ROS homeostasis and membrane-lipid stability under stressful conditions. Moreover, the expression of stress-associated genes was positively regulated in overexpression of MfWRKY70 Arabidopsis. We proposed that MfWRKY70 may function as a positive regulator for abiotic stress responses and can be considered as a potential gene for improvement of drought and salinity tolerance in plants.

Technical Abstract: The resurrection plants Myrothamnus flabellifolia could survive from long term severely drought and desiccation conditions and soon recover after rewatering. However, few genes related to such excellent drought tolerance and underlying molecular mechanism have been excavated. WRKY transcription factors play critical roles in biotic and abiotic stress signaling, in which WRKY70 functions as positive regulator in biotic stress response but negative regulator in abiotic stress signaling in Arabidopsis and some other plant species. In the present study, the functions of a dehydration-induced MfWRKY70 of M. flabellifolia participating was investigated in model plant Arabidopsis. Our results indicated that MfWRKY70 was localized in the nucleus and could significantly increase tolerance to drought, osmotic, and salinity stresses by promoting root growth, water retention, as well as enhancing antioxidant enzyme system and maintaining ROS homeostasis and membrane-lipid stability under stressful conditions. Moreover, the expression of stress-associated genes (P5CS, NCED3, and RD29A) was positively regulated in overexpression of MfWRKY70 Arabidopsis. We proposed that MfWRKY70 may function as a positive regulator for abiotic stress responses and can be considered as a potential gene for improvement of drought and salinity tolerance in plants.