Identification of drought, cadmium and root-lesion nematode infection stress-responsive transcription factors in ramie

Drought, cadmium (Cd) stress, and root lesion nematode (RLN) infection are three of the most important stresses affecting ramie growth and development; therefore, ramie breeding programs focus on their management more than on any other abiotic or biotic stresses. The fact that only a small number of stress-responsive transcription factors (TFs) have been identified so far is a major obstacle in the elucidation of mechanisms regulating the response to these three stresses in ramie. In this study, in order to uncover more stress-responsive TFs, a total of 179 non-redundant genes with full-length open reading frames from the MYB, AP2/ERF, bZIP, HD-ZIP, and COL families were obtained by searching for against the ramie transcriptome. Expression pattern analysis demonstrated that most of these genes showed relatively higher expression in the stem xylem and bast than in other tissues. Among these genes, 96 genes were found to be involved in responses to drought, Cd exposure, or RLN-infection. The expression of 54 of these genes was regulated by at least two stresses. These stress-responsive TFs probably have roles in the regulation of stress tolerance. The discovery of these stress-responsive TFs will be helpful for furthering our understanding of the mechanisms that regulate stress responses in ramie.