State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, 311300, People's Republic of China.
Center for Cultivation of Subtropical Forest Resources (CCSFR), Zhejiang A&F University, Hangzhou, 311300, People's Republic of China.
Mol Biol Rep. 2020 Jun;47(6):4495-4506. doi: 10.1007/s11033-020-05529-w. Epub 2020 May 22.
The GH3 genes play vital roles in auxin homeostasis by conjugating excess auxin to amino acids. However, how GH3 genes function during grafting in Chinese hickory (Carya cathayensis) is largely unknown. Here, based on the transcriptome database, a comprehensive identification and expression profiling analysis of 12 GH3 genes in Chinese hickory were performed. Phylogenetic analysis indicated that CcGH3-x exists in a specific subfamily. To understand the roles of CcGH3 genes, tissue-specific expression and the response to different phytohormones were determined. Expression profiles of GH3 genes of Chinese hickory during grafting were analysed. The data suggested that 10 CcGH3 genes were down-regulated at an early stage of grafting, indicating that auxin homeostasis regulated by the CcGH3 family might be inhibited at initial stages. At the completion of grafting, expression levels of members of the CcGH3 family were restored to normal levels. Endogenous auxin levels were also measured, and the data showed that free auxin decreased to the lowest level at an early stage of grafting, and then increased during grafting. Auxin amino acid conjugation increased at an early stage of grafting in rootstock, and then decreased with progression of the graft union. Our results demonstrate that the reduced expression of CcGH3 family genes during grafting might contribute to the release of free auxin, making an important contribution to the recovery of auxin levels after grafting.
GH3 基因通过将过量的生长素与氨基酸结合，在生长素稳态中发挥着重要作用。然而，GH3 基因在山核桃（Carya cathayensis）嫁接过程中的功能仍知之甚少。本研究基于转录组数据库，对山核桃 12 个 GH3 基因进行了全面鉴定和表达谱分析。系统发育分析表明，CcGH3-x 存在于一个特定的亚家族中。为了了解 CcGH3 基因的作用，我们测定了其组织特异性表达和对不同植物激素的响应。分析了山核桃嫁接过程中 GH3 基因的表达谱。数据表明，10 个 CcGH3 基因在嫁接的早期阶段下调，表明由 CcGH3 家族调节的生长素稳态可能在初始阶段受到抑制。在嫁接完成时，CcGH3 家族成员的表达水平恢复到正常水平。还测量了内源生长素水平，数据显示游离生长素在嫁接早期降至最低水平，然后在嫁接过程中增加。嫁接过程中砧木中生长素氨基酸结合物在早期增加，然后随着嫁接结合的进展而减少。我们的研究结果表明，嫁接过程中 CcGH3 家族基因的低表达可能有助于游离生长素的释放，为嫁接后生长素水平的恢复做出了重要贡献。
