Characterization of 33 HbbZIP Gene Family Members and Analysis of Their Expression Profiles in Rubber Tree in Response to ABA, Glyphosate and Powdery Mildew Treatment

Abstract

Plant bZIP transcription factors play important roles in nearly all biological processes. Elucidation of the potential functions of these proteins in rubber trees will help to improve breeding and cultivation techniques. Here, we identified 33 HbbZIP family genes based on genomic data and named them according to their homologs in Arabidopsis thaliana. The genes were divided into 10 subgroups, namely, A to I. All the proteins had three motifs that varied in the different subgroups. The exons and introns were also analyzed on the basis of DNA sequence analysis. Expression analysis revealed that the 33 HbbZIPs were expressed primarily in the flowers, followed by the leaves and roots, while the lowest expression was detected in the latex and bark. In response to ABA treatment, the genes were significantly differentially expressed. The highest HbbZIP38 level increased by approximately 21-fold, and the lowest HbbZIP56 level decreased by 21-fold. In response to powdery mildew infection, most HbbZIPs were upregulated at 6 h after treatment; however, HbbZIP58 and HbbZIP47 were downregulated at this time point. In response to glyphosate, the expression of only HbbZIP21 and HbbZIP38 decreased, while that of the other HbbZIP proteins increased. Taken together, these results suggested that members of the different HbbZIP subgroups have specific functions. Overall, this study lays a solid foundation for further exploration of the potential roles of HbbZIPs in rubber trees.