The Mechanism of Micrografting With Salt-Tolerant Rootstock in Improving the Salt Tolerance of Scion in Vitis vinifera.

Grapevine (Vitis vinifera L.) is highly sensitive to soil salinization, which severely restricts its cultivation in salt-affected areas. In this study, "Pinot Noir" (V. vinifera "Pinot Noir") was micro-grafted onto the salt-tolerant rootstock "Kangzhen No. 3" to explore the mechanisms by which rootstock-mediated micrografting enhances scion salt tolerance. Grafted seedlings, un-grafted scions, and rootstocks were irrigated with 200 mmol/L NaCl for 6 days. Physiological assessments and transcriptomic analysis revealed that grafted plants exhibited significantly improved salt tolerance compared to ungrafted "Pinot Noir." Differentially expressed genes were mainly enriched in plant hormone signal transduction, MAPK signaling, and phenylpropanoid biosynthesis pathways. Two key genes, VvFLS and VvGSTU14, were selected for functional validation. Overexpression in grapevine calli enhanced antioxidant capacity and significantly improved salt tolerance. These findings demonstrate that micrografting with a salt-tolerant rootstock can enhance scion performance under saline stress by modulating key signaling and metabolic pathways, providing a theoretical foundation for grapevine improvement and sustainable production on saline soils.