Sorghum WRKY transcription factor SbWRKY45 enhanced seed germination under drought stress in transgenic Arabidopsis

Abstract

The WRKY transcription factors (TFs) family is an important family of plant-specific TFs, playing vital roles in various abiotic and biotic stress responses. WRKY TFs are gaining considerable attention due to their significant roles in stress responses. However, their functions in sorghum (Sorghum bicolor) are lagging behind. In this study, a WRKY gene designated as SbWRKY45 was isolated and characterized from sorghum. SbWRKY45, belonging to Group IIa, consists of one intron and two exons and encodes 430 amino acids. SbWRKY45 is located in chromosome 4. The cis-element prediction analysis showed that the promoter region of SbWRKY45 has several abiotic stress-associated elements. The qRT-PCR results showed that SbWRKY45 was significantly up-regulated in response to drought and cold under salt treatments, was notably changed, and was induced weakly under heat stress. SbWRKY45 exhibited a response to stress in different sorghum tissues, including leaves, stems, and roots. A tissue-specific expression pattern showed that SbWRKY45 was highly expressed in roots compared with leaves and stems, suggesting that SbWRKY45 may play an important role in roots. Overexpression of SbWRKY45 increased germination rates and promoted root growth in transgenic Arabidopsis under drought stress. Taken together, our findings indicate that SbWRKY45 may be involved in mediating the response to drought stress and play a vital role in the abiotic stress response of sorghum