Synergistic Regulation by FaTRAB1 and FaGAPC2 Enhances Strawberry Resistance to Tetranychus urticae through Trichome Density Modulation, Lignin Accumulation, and Insect-Resistant Metabolite Biosynthesis

Trichomes are key physical and chemical barriers in plants against herbivorous insects, but their development and role in strawberry insect resistance remain unclear. This study found that overexpressing FaGAPC2, a glycolytic gene, increased glandular trichome density and nonglandular trichome density while raising lignin content by 26.8%. Multiomics analysis revealed that FaGAPC2 activates phenylpropanoid biosynthesis, boosting levels of hydroferulic acid, kaempferol, and tetrandrine, reducing Tetranychus urticae damage by 61.5-82.8%. Y1H, LUC, and EMSA assays confirmed that bZIP transcription factor FaTRAB1 directly activates FaGAPC2. FaTRAB1 overexpression enhanced trichome density, pectin/cellulose content, and lignin accumulation by upregulating FaCSE and FaHCT while increasing the leaf thickness, forming a robust mechanical barrier. These findings demonstrate how the FaTRAB1-FaGAPC2 module enhances mite resistance via trichome development, lignin deposition, and insecticidal metabolite synthesis, offering new strategies for breeding pest-resistant strawberries and developing plant-based acaricides.