College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetables Genetic Improvement, Ministry of Agriculture, Nanjing, 210095, China.
Center for Environment, Health and Field Science, Chiba University, Kashiwa-no-ha 6-2-1, Kashiwa, Chiba, Japan.
Plant Physiol Biochem. 2018 Aug;129:368-380. doi: 10.1016/j.plaphy.2018.06.021. Epub 2018 Jun 19.
Grafting is a widely used technique, and graft compatibility between the rootstock and scion is a prerequisite for grafting. To date, the underlying causes of graft compatibility/incompatibility remain largely unknown. Here, using cucumber (Cucumis sativus L.) grafted onto pumpkin (Cucurbita L.) rootstocks with different degrees of graft compatibility, and both self-grafting and non-grafting as controls, an integrative analysis of mRNA and miRNA expression and regulatory networks was conducted by using RNA-Seq and sRNA-Seq at 25 days after grafting (DAG). A total of 223 differentially expressed genes (DEGs) and 30 differentially expressed miRNAs (DEMs) related to graft compatibility were identified based on their fold change. Using a combination of GO annotations and KEGG pathway data, the functional annotations and pathways of DEGs and DEM targets showed that a number of metabolic, physiological and hormonal responses are involved in graft compatibility in cucumber leaves including metabolic processes (e.g., "carbohydrate metabolic processes"), nutrient transport (e.g., "sugar transport"), signal transduction (e.g., "MAPK cascade"), plant hormone signal transduction (e.g., "abscisic acid-activated signaling pathway"), transcription factors (e.g., MYB, NAC and bHLH), oxidation-reduction processes, and defense responses. The results of our comprehensive analysis suggested that compatible rootstocks might possess a greater ability for cell proliferation and a more efficient carbohydrate metabolism that promotes plant growth. In contrast, incompatible grafts induced multiple defense response-related genes and various transcription factors, likely in response to stress. Additionally, they consumed large amounts of energy, which ultimately restrained the plants normal development. This study advances our understanding of the molecular mechanisms underlying plant graft compatible/incompatible responses and provides numerous mRNA and miRNA candidates for more in-depth studies into the graft compatibility process.
嫁接是一种广泛应用的技术，砧木和接穗之间的嫁接相容性是嫁接的前提。迄今为止，嫁接相容性/不相容性的根本原因在很大程度上仍然未知。在这里，使用黄瓜（Cucumis sativus L.）嫁接到具有不同程度嫁接相容性的南瓜（Cucurbita L.）砧木上，并以自嫁接和非嫁接作为对照，通过 RNA-Seq 和 sRNA-Seq 在嫁接后 25 天（DAG）对 mRNA 和 miRNA 表达及调控网络进行综合分析。基于倍数变化，共鉴定出 223 个与嫁接相容性相关的差异表达基因（DEGs）和 30 个差异表达 miRNA（DEMs）。通过 GO 注释和 KEGG 途径数据的组合，DEGs 和 DEM 靶标的功能注释和途径表明，在黄瓜叶片中，许多代谢、生理和激素反应参与了嫁接相容性，包括代谢过程（例如，“碳水化合物代谢过程”）、养分运输（例如，“糖运输”）、信号转导（例如，“MAPK 级联”）、植物激素信号转导（例如，“脱落酸激活的信号通路”）、转录因子（例如，MYB、NAC 和 bHLH）、氧化还原过程和防御反应。我们综合分析的结果表明，相容砧木可能具有更强的细胞增殖能力和更有效的碳水化合物代谢能力，从而促进植物生长。相比之下，不相容嫁接诱导了多个与防御反应相关的基因和各种转录因子，可能是对胁迫的反应。此外，它们消耗大量能量，最终抑制了植物的正常发育。本研究提高了我们对植物嫁接相容/不相容反应分子机制的理解，并为深入研究嫁接相容性过程提供了众多 mRNA 和 miRNA 候选基因。
