Luo Guangbao, Huang Xinran, Chen Jiawei, Luo Jinying, Liu Yufei, Tang Yunfei, Xiong Mu, Lu Yongen, Huang Yuan, Ouyang Bo
Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China.
Shenzhen Institute of Nutrition and Health, Huazhong Agricultural University, Shenzhen 518120, China.
Plants (Basel). 2022 Aug 11;11(16):2092. doi: 10.3390/plants11162092.
Grafting is an important agricultural practice to control soil-borne diseases, alleviate continuous cropping problems and improve stress tolerance in vegetable industry, but it is relatively less applied in pepper production. A recent study has revealed the key roles of β-1, 4-glucanase in graft survival. We speculated that the GH9 family gene encoding glucanase may be involved in the obstacles of pepper grafting. Therefore, we performed a systematic analysis of the GH9 family in pepper, tomato and tobacco. A total of 25, 24 and 42 GH9 genes were identified from these three species. Compared with the orthologues of other solanaceous crops, the deduced pepper GH9B3 protein lacks a conserved motif (Motif 5). Promoter cis-element analysis revealed that a wound-responsive element exists in the promoter of tobacco , but it is absent in the GH9B3 promoter of most solanaceous crops. The auxin-responsive related element is absent in promoter, but it presents in the promoter of tobacco, tomato, potato and petunia GH9B3. Tissue and induction expression profiles indicated that GH9 family genes are functionally differentiated. Nine GH9 genes, including , were detected expressing in pepper stem. The expression patterns of and in grafting were different in our test condition, with obvious induction in tobacco but repression in pepper. Furthermore, weighted correlation network analysis (WGCNA) revealed 58 transcription factor genes highly co-expressed with . Eight WRKY binding sites were detected in the promoter of , and several were highly co-expressed with . In conclusion, the missing of Motif 5 in CaGH9B3, and lacking of wound- and auxin-responsive elements in the gene promoter are the potential causes of grafting-related problems in pepper. family transcription factors could be important regulator of in tobacco grafting. Our analysis points out the putative regulators of , which would be helpful to the functional validation and the study of signal pathways related to grafting in the future.
嫁接是蔬菜产业中防治土传病害、缓解连作问题和提高抗逆性的一项重要农艺措施，但在辣椒生产中的应用相对较少。最近的一项研究揭示了β-1,4-葡聚糖酶在嫁接成活中的关键作用。我们推测编码葡聚糖酶的GH9家族基因可能与辣椒嫁接障碍有关。因此，我们对辣椒、番茄和烟草中的GH9家族进行了系统分析。从这三个物种中分别鉴定出25个、24个和42个GH9基因。与其他茄科作物的直系同源基因相比，推导的辣椒GH9B3蛋白缺少一个保守基序（基序5）。启动子顺式元件分析表明，烟草启动子中存在一个伤口响应元件，但在大多数茄科作物的GH9B3启动子中不存在。生长素响应相关元件在辣椒启动子中不存在，但在烟草、番茄、马铃薯和矮牵牛的GH9B3启动子中存在。组织和诱导表达谱表明GH9家族基因在功能上存在分化。包括CaGH9B3在内的9个GH9基因在辣椒茎中被检测到表达。在我们的试验条件下，CaGH9B3和NbGH9B3在嫁接中的表达模式不同，在烟草中明显诱导表达而在辣椒中受到抑制。此外，加权基因共表达网络分析（WGCNA）揭示了58个与NbGH9B3高度共表达的转录因子基因。在CaGH9B3启动子中检测到8个WRKY结合位点，且有几个WRKY基因与CaGH9B3高度共表达。总之，CaGH9B3中基序5的缺失以及该基因启动子中伤口和生长素响应元件的缺失是辣椒嫁接相关问题的潜在原因。WRKY家族转录因子可能是烟草嫁接中NbGH9B3的重要调节因子。我们的分析指出了CaGH9B3的假定调节因子，这将有助于未来对其功能验证以及与嫁接相关信号通路的研究。
