Huang Qiaoyu, Liu Haixia, Shen Qinyuan, Yuan Huwei, Cui Fuqiang, Yan Daoliang, Ding Wona, Wang Xiaofei, Zheng Bingsong
National Key Laboratory for Development and Utilization of Forest Food Resources, Zhejiang A&F University, Hangzhou 311300, China.
Provincial Key Laboratory for Non-Wood Forest and Quality Control and Utilization of Its Products, Zhejiang A&F University, Hangzhou 311300, China.
Plants (Basel). 2025 Jul 18;14(14):2229. doi: 10.3390/plants14142229.
Grafting involves complex hormonal interactions at graft interfaces that are not yet fully understood. In this study, we analyzed hormone fluctuations and gene expression during callus proliferation and vascular tissue differentiation in hickory ( Sarg.) grafts. Cytokinin and ethylene precursor ACC levels steadily increased after grafting. The biosynthetic genes for these hormones (, , , and ) exhibited heightened expression. Genes related to cytokinin signaling (, , and ) and ethylene signaling (, , and ) were similarly upregulated. Conversely, genes associated with jasmonic acid, abscisic acid, and strigolactone pathways were downregulated, including synthesis genes ( and ) and those involved in signal transduction (, , and ). Correspondingly, JA-Ile and 5-deoxystrigol levels significantly decreased. Indole-3-acetic acid (IAA) levels also dropped during the early stages of graft union formation. These results suggest that low auxin concentrations may be essential in the initial stages after grafting to encourage callus proliferation, followed by an increase at later stages to facilitate vascular bundle differentiation. These findings imply that maintaining a balance between low auxin levels and elevated cytokinin and ethylene levels may be critical to support cell division and callus formation during the initial proliferation phase. Later, during the vascular differentiation phase, a gradual rise in auxin levels, accompanied by elevated ethylene, may facilitate the differentiation of vascular bundles in hickory grafts.
嫁接涉及嫁接界面处复杂的激素相互作用，目前尚未完全了解。在本研究中，我们分析了山核桃（Sarg.）嫁接过程中愈伤组织增殖和维管组织分化过程中的激素波动和基因表达。嫁接后细胞分裂素和乙烯前体ACC水平稳步上升。这些激素的生物合成基因（，，，和）表达增强。与细胞分裂素信号传导相关的基因（，，和）和乙烯信号传导相关的基因（，，和）同样上调。相反，与茉莉酸、脱落酸和独脚金内酯途径相关的基因被下调，包括合成基因（和）以及参与信号转导的基因（，，和）。相应地，茉莉酸异亮氨酸和5-脱氧独脚金醇水平显著降低。在嫁接愈合形成的早期阶段，吲哚-3-乙酸（IAA）水平也下降。这些结果表明，低生长素浓度在嫁接后的初始阶段可能对促进愈伤组织增殖至关重要，随后在后期阶段增加以促进维管束分化。这些发现意味着在初始增殖阶段，维持低生长素水平与升高的细胞分裂素和乙烯水平之间的平衡对于支持细胞分裂和愈伤组织形成可能至关重要。后来，在维管分化阶段，生长素水平的逐渐升高，伴随着乙烯的升高，可能促进山核桃嫁接中维管束的分化。
