Overview of the samples for RNA-seq.

Camellia chekiangoleosa is a significant oil-bearing tree species, known for its high oleic acid content and shorter reproductive cycle compared to traditional oil-tea plants. However, there are few studies on the molecular mechanism and compatibility of the interaction between oil-Camellia scion and rootstock, which poses certain challenges to the cultivation and promotion of oil-Camellia. This study systematically evaluates the effects of hetero-grafting Camellia chekiangoleosa scions onto divergent rootstocks (Camellia chekiangoleosa, Camellia oleifera, and Camellia yuhsienensis). Then the research investigates how rootstock selection alters scion growth and development through phenotypic, biochemical, and transcriptomic analyses. Our findings reveal that the combination of C. oleifera scion grafted onto C. yuhsienensis suppresses auxin (IAA) and cytokinin (ZR) levels while elevating abscisic acid (ABA). Transcriptomic analysis identified that the PYL1, AMY, and INV1 screened by transcriptome data were mainly enriched in starch and sucrose metabolic pathways and plant hormone signal transduction, which collectively prioritize carbon allocation toward growth over storage. Meanwhile, hetero-grafting improved photosynthetic capacity by upregulating light-harvesting complex (LHC) genes and carotenoid biosynthesis enzymes (ZEP), optimizing light energy conversion and photoprotection. These findings provide novel insights into the molecular mechanisms underlying rootstock-scion interactions in oil-Camellia, bridging a critical knowledge gap in this economically important genus.

浙江红山茶（Camellia chekiangoleosa）是一种重要的油料树种，相较于传统油茶类植物，其油酸含量更高、生殖周期更短，具备优异的应用潜力。然而，当前针对油茶接穗与砧木互作的分子机制及亲和性的研究仍较为匮乏，这为油茶的栽培与推广带来了一定挑战。本研究系统评估了将浙江红山茶接穗嫁接至三种不同砧木（浙江红山茶、油茶（Camellia oleifera）、攸县油茶（Camellia yuhsienensis））的异源嫁接组合效果。随后，通过表型、生化及转录组分析，探究了砧木选择如何调控接穗的生长发育过程。研究结果显示，以油茶为接穗、攸县油茶为砧木的嫁接组合，会抑制生长素（IAA）与细胞分裂素（ZR）的积累，同时提升脱落酸（ABA）的水平。转录组分析表明，筛选得到的PYL1、AMY与INV1基因主要富集于淀粉与蔗糖代谢通路及植物激素信号转导通路，这些通路共同促使碳分配倾向于生长而非储存。此外，异源嫁接可通过上调捕光复合体（LHC）基因及类胡萝卜素合成酶（ZEP）的表达，提升植株的光合能力，优化光能转化与光保护机制。本研究结果为油茶属砧穗互作的分子机制提供了全新的研究视角，填补了这一具有重要经济价值的植物属的相关研究的关键知识空白。