VqERF1B-VqERF062-VqNSTS2 transcriptional cascade enhances stilbene biosynthesis and resistance to powdery mildew in grapevine

Abstract

Grapes, as one of the world's oldest economic crops, are severely affected by grape powdery mildew, causing significant economic losses. As a phytoalexin against powdery mildew, stilbenes and their key synthetic gene, stilbene synthase (STS), are highly sought after by researchers. In our previous research, a new gene, VqNSTS2, was identified from Vitis quinquangularis accession 'Danfeng-2' through transcriptomic analysis. However, the function and molecular mechanism of VqNSTS2 gene remain unknown. Here, by characterization and transient overexpression of VqNSTS2, we demonstrated that its expression product, stilbenes, can be detected in the model plant tobacco, which does not inherently contain STSs. After artificially inoculating transgenic Arabidopsis lines overexpressing VqNSTS2 with Erysiphe necator, it was found that VqNSTS2 actively moved to the pathogen's haustorium after responding to the pathogen, recognized and enveloped the haustorium, blocking the pathogen's infection and invasion and exhibited disease resistance. Furthermore, Agrobacterium-mediated stable overexpression of VqNSTS2 promoted stilbene accumulation and enhanced resistance of the V. vinifera susceptible cultivar 'Thompson Seedless' to E. necator. Additionally, through screening and identification, a transcription factor, VqERF062, was found to directly bind to the DRE and RAA motifs on ProVqNSTS2, positively regulating VqNSTS2 expression. Moreover, VqERF062 directly interacted with VqERF1B to promote the transcription of VqNSTS2 in addition to forming a homodimer with itself. Taken together, our findings reveal that the VqERF1B-VqERF062- module is required for grape resistance to E. necator and providing insights into the regulatory mechanism of stilbenes biosynthesis.