PhebZIP47, a bZIP transcription factor from moso bamboo (Phyllostachys edulis), positively regulates the drought tolerance of transgenic plants

The bZIP transcription factor (TF) family plays indispensable roles in plant response to environmental stresses. However, little is known about the functional roles of bZIP genes in moso bamboo (Phyllostachys edulis). Here, transcriptome data from public databases was used to analyse the expression patterns of 154 bZIP genes, and the results exhibited that the expression of many bZIP genes were strongly induced by drought. Combined with weighted gene co-expression network and qRT-PCR analysis, we screened a key candidate gene PhebZIP47 in response to drought and ABA. Next, the lines of transgenic PhebZIP47-overexpressing Arabidopsis and rice were generated. Transgenic plants showed enhanced resistance to drought at the seed germination and adult stage. Measurements of physiological indicators including chlorophyll content, relative water content, electrical con-ductivity, malondialdehyde and proline content were used to support this conclusion. Transcriptome analysis of transgenic rice showed that there were a large number of differentially expressed genes (DEGs) regulated by PhebZIP47, including genes of drought tolerance regulatory pathway and ABA signalling pathway. Meanwhile, a G-box element was significantly enriched in the promoters of the DEGs annotated as 'response to stress', and EMSA experiment suggested that this element could be bound by PhebZIP47. In addition, transgenic plants were less sensitive to ABA compared with wild-type plants under exogenous ABA treatment. Overall, our study pro-vided a key candidate gene for the molecular breeding of moso bamboo and laid a foundation for the study of drought-resistance mechanism of bZIP genes.