A dual-functional laccase gene CsLAC17 from tea plant: Insights from VIGS and heterologous expression into lignin-mediated resistance and direct antifungal activity

Tea ( Camellia sinensis (L.) O. Kuntze) is a globally significant beverage crop, yet its production is frequently compromised by various fungal diseases, therefore, enhancing its natural disease resistance is of great importance. Laccases (LACs) are key enzymes in plant defense responses. Here, we identified and functionally characterized a tea laccase gene, CsLAC17 , which has a full length of 1758 bp and encodes 585 amino acids. Silencing CsLAC17 in tea via virus-induced gene silencing (VIGS) significantly compromised resistance to anthracnose, accompanied by elevated MDA content. Its overexpression in tobacco increased lignin content and boosted resistance to Botrytis cinerea . Furthermore, the purified CsLAC17 protein, heterologously expressed in yeast, directly inhibited the growth of B. cinerea in vitro. These results indicate that CsLAC17 enhances plant systemic resistance by regulating lignin biosynthesis, and that its encoded protein also possesses direct antifungal activity. This finding not only provides new insights into tea disease resistance mechanisms but also offers a dual target for breeding disease-resistant cultivars and developing novel green fungicides.