Transcription Profiling of Glycosyltransferases in Cultivars Following Smoke Exposure.

Smoke taint is a fault that can occur in wines made from smoke-affected grapes. Smoke taint research has largely focused on chemical and sensory analysis and mitigation strategies, with limited attention to underlying molecular responses. We performed RNA sequencing on berries from cultivars Shiraz and Chardonnay after controlled smoke exposure. Significant transcript upregulation was observed in smoke-affected grapes, especially for heat shock proteins (HSP20s) and glycosyltransferases (GTs). Chardonnay showed upregulation of 15 GTs from GT1, GT8, GT32, GT47, and GT90, while Shiraz had only five upregulated GTs, primarily GT1 and GT8, suggesting cultivar-specific responses. Gene Ontology enrichment indicated activation of phenylpropanoid and xenobiotic response pathways. While prior studies focused on GT1, our results highlight potential roles for other GT families, particularly GT8. These findings expand our understanding of grapevine stress responses to smoke and identify new molecular targets to inform future strategies for managing smoke taint in grape production.