Cloning and functional analysis of PebZIP26 and PebZIP33 transcription factors from Populus euphratica

bZIP (basic region/leucine zipper motif) transcription factor is a kind of large transcription factor family and widely distributed in eukaryotic organisms. It participates in the regulation of plant growth and development, senescence, hormone regulation, energy metabolism, pathogen defense, etc. Populus euphratica is a model woody plant to study the molecular mechanism of plant resistance, and has excellent resistance ability to stress, but there are fewer reports about its bZIPs function. We cloned PebZIP26 and PebZIP33 cDNA from Populus euphratica, encoding 439 and 371 amino acids, respectively. The expression of PebZIP26 and PebZIP33 genes were induced by drought, dehydration and salt stress, and then constructed expression vectors. The wild type Arabidopsis thaliana was transformed by Agrobacterium tumefaciens infection, and different strains of CaMV35S: PebZIP26 and CaMV35S: PebZIP33 and vacant carrier were obtained. The root length of PebZIP26 and PebZIP33 lines were longer than that of wild type on 150 mmol/L NaCl and 300 mmol/L Mannitol medium, and had a better leaf statement. 21days drought and salt treatment on each strains of pot plants revealed that, the PebZIP26 and PebZIP33 lines showed better salt tolerance and drought resistance with better nutritional growth and the height of main branch was taller than WT and vacant carrier, and the survival rate after re-watering was 61% and 48%, significantly higher than WT(9%) and vacant carrier(12%). In the stomatal closure experiment, the PebZIP26 and PebZIP33 strains were more sensitive to exogenous ABA than WT, abf1 and tga1(arabidopsis homologous gene ABF1 and TGA1 mutant), and also improved the antioxidant activity of plants. Therefore, the study showed that PebZIP26 and PebZIP33 transcription factors could improve the abiotic stress resistance, further enrich the functional study of bZIP genes in woody plants, and provide genetic resources and theoretical basis for genetic breeding.