A class III WRKY transcription factor in sugarcane was involved in biotic and abiotic stress responses.

WRKY transcription factors play significant roles in plant stress responses. In this study, a class III WRKY gene ScWRKY5, was successfully isolated from sugarcane variety ROC22. The ScWRKY5 was a nucleus protein with transcriptional activation activity. The ScWRKY5 gene was constitutively expressed in all the sugarcane tissues, with the highest expression level in the stem epidermis and the lowest in the root. After inoculation with Sporisorium scitamineum for 1 d, the expression level of ScWRKY5 was significantly increased in two smut-resistant varieties (YZ01-1413 and LC05-136), while it was decreased in three smut-susceptible varieties (ROC22, YZ03-103, and FN40). Besides, the expression level of ScWRKY5 was increased by the plant hormones salicylic acid (SA) and abscisic acid (ABA), as well as the abiotic factors polyethylene glycol (PEG) and sodium chloride (NaCl). Transient overexpression of the ScWRKY5 gene enhanced the resistance of Nicotiana benthamiana to the tobacco bacterial pathogen Ralstonia solanacearum, however the transiently overexpressed N. benthamiana was more sensitive to the tobacco fungal pathogen Fusarium solani var. coeruleum. These results provide a reference for further research on the resistance function of sugarcane WRKY genes.