Integrated transcriptomic and metabolomic analyses reveal the regulatory network of alkaloid metabolism in blister blight-infected tea plants

Abstract

Blister blight disease, caused by the fungus Exobasidium vexans , severely threatens tea production and yield. This study investigates the molecular and metabolic responses of tea to blister blight infection, with a focus on alkaloid metabolism. Here, integrated transcriptomics and metabolomics were employed to investigate the differences between healthy leaves and infected leaves at three disease stages. In total, 79 alkaloid metabolites were identified, with 30 differential metabolites shared across all infection stages. Transcriptome sequencing revealed 846 differentially expressed genes, many of which were enriched in the isoquinoline alkaloid biosynthesis pathway. Key structural genes (e.g. TAT , PPO ) and transcription factors (e.g., WRKY , GRAS ) were significantly upregulated during infection, correlating with altered alkaloid profiles. Notably, dopamine, a key intermediate, was downregulated, suggesting a potential shift in metabolic flux toward downstream defense-related alkaloid synthesis. qRT-PCR validation confirmed the expression patterns of selected DEGs. Our findings provide the first comprehensive evidence that alkaloid metabolism, particularly the isoquinoline alkaloid pathway, are transcriptionally and metabolically reprogrammed during blister blight infection, suggesting a potential role in tea’s defense against this pathogen. These results offer valuable insights for breeding resistant tea cultivars.