CsNAC083 and CsVND1 are associated with tea plant leaf angle through xylem development and lignin deposition

Tea (Camellia sinensis) is an important perennial horticultural crop, but the genetic control of leaf angle, a key trait affecting plant architecture and harvesting efficiency, remains unclear. In this study, we measured leaf angles at different leaf positions and examined the anatomy of the bending region between the leaf midrib and the main stem across 12 tea cultivars. Hongyan 1(HY 1) with large leaf angles and Hongyan 4(HY 4) with small leaf angles were selected for transcriptome analysis. Differentially expressed genes were mainly enriched in hormone signaling, MAPK signaling, and phenylpropanoid biosynthesis pathways. Two NAC transcription factors, CsNAC083 and CsVND1, were prioritized as candidates, and their expression patterns were examined by qRT-PCR. Sequence and phylogenetic analyses suggested that CsNAC083 is associated with inhibition of xylem differentiation, while CsVND1 is related to xylem formation and lignin deposition. Both proteins localized to the nucleus and showed direct interaction in yeast. Heterologous expression in tobacco showed that CsNAC083 overexpression was associated with increased leaf bending by reducing xylem differentiation and lignin deposition, whereas CsVND1 enhanced lignification and promoted leaf erectness. Co-expression of CsVND1 partially alleviated the phenotypes caused by CsNAC083 overexpression. These findings reveal a regulatory mechanism linking vascular development to leaf angle formation in tea plants and provide a potential genetic basis for optimizing plant architecture in tea cultivation.