The BpZAT10-BpWRKY31 module enhances the drought tolerance and herbivore resistance of Betula platyphylla through the jasmonic acid signalling pathway

Abstract

Birch (Betula platyphylla) is an important native species widely distributed in northeastern China. It faces various adverse environmental challenges during its natural growth, including drought and herbivory. Here, we identified a transcriptional regulatory module in birch, BpZAT10-BpWRKY31, that increases drought tolerance and gypsy moth (Lymantria dispar) resistance. Overexpressing BpZAT10 or BpWRKY31 improved ROS scavenging, reduced oxidative damage under drought conditions, and increased the antifeedant effects against the gypsy moth in both selective and nonselective antifeeding experiments, whereas knockout lines exhibited heightened susceptibility. BpZAT10 binds directly to the TGACG motif in the promoter of BpWRKY31, a downstream gene in the BpZAT10-centred gene regulatory network, thereby activating its expression. BpWRKY31 in turn promotes jasmonic acid (JA) accumulation and activates flavonoid biosynthesis-related pathways by binding to W-box elements in the promoters of JA biosynthesis-related genes (BpLOX15, BpAOS1, BpAOS2, and BpAOC4) and flavonoid pathway-initiating phenylalanine ammonia lyase genes (BpPAL4 and BpPAL5). Inhibition of JA reduced the stress resistance phenotypes associated with BpZAT10 and BpWRKY31 overexpression, supporting the involvement of JA signalling in this module. In conclusion, this study reveals a hierarchically organised BpZAT10-BpWRKY31 module that couples JA signalling and flavonoid biosynthesis-related pathways, laying a theoretical foundation for the further cultivation of trees with excellent stress resistance.