Lily WRKY factor LlWRKY22 promotes thermotolerance through autoactivation and activation of LlDREB2B

Ze Wu; Ting Li; Xing Cao; Dehua Zhang; Nianjun Teng

doi:10.1093/hr/uhac186

Lily WRKY factor LlWRKY22 promotes thermotolerance through autoactivation and activation of LlDREB2B

Hortic Res. 2022 Aug 25:9:uhac186. doi: 10.1093/hr/uhac186. eCollection 2022.

Authors

Ze Wu^{1

2

3}, Ting Li^{1

2}, Xing Cao⁴, Dehua Zhang^{1

2}, Nianjun Teng^{1

2}

Affiliations

¹ Key Laboratory of Landscaping Agriculture, Ministry of Agriculture and Rural Affairs/Key Laboratory of Biology of Ornamental Plants in East China, National Forestry and Grassland Administration, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
² Jiangsu Graduate Workstation of Nanjing Agricultural University and Nanjing Oriole Island Modern Agricultural Development Co., Ltd, Nanjing 210043, China.
³ College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
⁴ College of Architecture, Yantai University, Yantai, 264005, China.

Abstract

Most of WRKY transcription factors play important roles in plant development, protection against disease, and response to abiotic stress; however, their roles in lily are largely unknown. Transcriptome analysis in lily (Lilium longiflorum) led to the identification and isolation of a WRKY-IIe gene, LlWRKY22, which was found to be activated at high temperature and play a positive role in thermotolerance regulation. LlWRKY22 expression was continuously activated by heat stress. We further found that LlWRKY22 protein localized to the nucleus and exhibited transactivation activity in both yeast and plant cells, and that its C terminus contributed to its transactivation activity. Meanwhile, overexpression of LlWRKY22 in lily improved thermotolerance and activated the expression of heat-related LlDREB2B gene; however, silencing of LlWRKY22 exerted the opposite effects. Further analysis revealed that LlWRKY22 directly activated the expression of LlDREB2B by binding to two tandem W-box elements on its promoter. Simultaneously, we also found that LlWRKY22 can directly bind its own promoter, thereby activating its own expression and forming a positive regulatory loop. Combined, our findings demonstrated that LlWRKY22 may be a new regulator of heat stress response and positively participates in the establishment of thermotolerance by activating itself and LlDREB2B.