Overexpression of lily LlWRKY22 enhances multiple abiotic stress tolerances in transgenic Arabidopsis

Abstract

In our previous study, a heat-induced differentially expressed WRKY-IIe gene LlWRKY22 is isolated from lily (Lilium longiflorum), which acts as a positive role in thermotolerance, but whether it is involved in other stress responses is unknown. Here, the expression of LlWRKY22 was indicated to be positively influenced by heat, salt, or mannitol treatments, and its promoter activity was also enhanced after heat, salt, or mannitol treatments. In addition, LlWRKY22 responded to ABA treatment, which activated its expression and also increased the promoter activity. Overexpression of LlWRKY22 in Arabidopsis contributed to growth defects and early flowering. Simultaneously, compared with the wild type, the ABA sensitivity in transgenic lines was increased in both the germination stage and late growth stage. Further analysis showed that LlWRKY22 overexpression elevated the thermotolerance of transgenic plants and induced the expression of AtDREB2A, AtDREB2B, AtDREB2C, and AtJUB1. The salt and mannitol tolerances of the overexpression lines were also improved. Overall, our results illustrated that LlWRKY22 is affected by heat, salt, and osmotic stresses, and positively regulates heat, salt, and osmotic tolerances, which reveals that it acts as a generalist character responding to different abiotic stresses. And further to that, the regulatory pathway of LlWRKY22 also involves in ABA signaling.

Keywords

• lilium longiflorum
• llwrky22
• abiotic stress
• aba
• thermotolerance