VvNUP96–VvTCP15 coupling regulates growth and salt tolerance via a VvmiR319c– <i>VvTCP4</i> module in grapevine

Soil salinity is a major abiotic stress that limits grapevine (Vitis vinifera) growth and productivity. Understanding the molecular basis of salt tolerance is therefore critical for breeding stress-resilient cultivars. Here, we identify a Class I TCP transcription factor, VvTCP15, whose salt-induced expression promotes growth under both normal and saline conditions, whereas its knockdown reduces growth and increases salt sensitivity. Further investigation reveals that VvTCP15 confers growth promotion and enhanced stress resilience by directly binding to the VvMIR319c promoter and activating its transcription. In turn, VvmiR319c acts as a positive regulator by targeting and cleaving VvTCP4 mRNA, a Class II CIN-like TCP factor that functions as a negative regulator of growth under both conditions. We further show that the nucleoporin VvNUP96 physically interacts with VvTCP15 and promotes the formation of nuclear condensates through the intrinsically disordered region of VvTCP15. This interaction stabilizes VvTCP15 and enhances its transcriptional activation of VvMIR319c. Genetic analyses place VvNUP96 upstream of VvTCP15 in regulating growth and salt tolerance. Together, these results define a VvNUP96-VvTCP15-VvmiR319c-VvTCP4 regulatory module that coordinates growth and salt stress responses in grapevine. This work reveals a functional link between nucleoporins and transcription factors via phase-separated condensates and provides potential targets for improving crop performance under saline conditions.