乙烯信号途径基因IbERF4参与甘薯抗根腐病的分子机制研究

Sweetpotato is an important crop as food, feed, industrial materials and new-type energy. However, the root rot affects the yield and quality of sweetpotato seriously. The main form of plant anti-disease is defense responses mediated by plant hormone signaling pathways. Previous studies have shown that ERFs transcription factors could regulate the expression of multiple genes participating in hormone signaling pathways, thereby activating the plant defense response. However, relative research on sweetpotato has been rarely reported. In this study, we use sweetpotato variety Xushu18, which possesses high resistance to root rot, as research material. Through transcriptome sequencing and RACE, we isolated IbERF4, which could be induced by ethylene, jasmonic acid, salicylic acid and root rot pathogen. Heterologous expression of IbERF4 in Arabidopsis and Tobacco confirmed that the gene participates in plant anti-disease. Therefore, we try to clarify the function and molecular mechanism of IbERF4 in root rot defense by genetic transformation next step, in order to exploring the feasibility of using genes that regulate sweetpotato anti-root rot in molecular breeding, which may provide new genetic resources for sweetpotato anti-disease breeding in future.

甘薯是重要的粮食、饲料、工业原料和新型能源作物，而根腐病的发生严重影响甘薯的产量与品质。植物激素信号传导途径介导的防卫反应是植物防御病害的主要形式。前期研究表明，ERFs转录因子可以协同调控多个激素信号途径中相关基因的表达，从而激活植物防卫反应，但关于ERFs转录因子通过激素信号传导激活甘薯抗病性的研究还鲜见报道。本研究以甘薯高抗根腐病品种徐薯18为研究材料，利用转录组测序结合RACE技术分离到一个同时受乙烯、茉莉酸、水杨酸等激素和根腐病病原菌诱导表达的基因IbERF4，通过异源表达IbERF4证实该基因参与植物抗病。项目拟通过甘薯转基因研究鉴定IbERF4功能，探索该基因在甘薯抗根腐病防卫反应中的抗性机理，以期探索利用抗根腐病反应关键调控基因进行甘薯抗病基因工程育种的可行性，为将来甘薯抗病基因工程育种提供新的基因资源。

甘薯是重要的粮食作物，根腐病的发生严重影响其产量和品质。研究表明，ERFs转录因子可以协同调控多个激素信号途径基因表达而激活植物防卫反应。项目前期从高抗根腐病品种徐薯18中分离到IbERF4基因，拟南芥中过表达IbERF4能够明显增强乙烯合成，并同时影响水杨酸、茉莉酸/乙烯信号途径病程相关基因表达；烟草瞬时表达系统证实IbERF4可以通过抑制烟草水杨酸信号途径病程相关基因表达而削弱植株对细菌性病害（Pseudomonase syringae pv. tabaci）的抗性。进一步研究发现，甘薯中过表达IbERF4能够削弱植株耐盐性和对黑斑病的抗性、增强对根腐病的抗性。通过酵母单杂交、双荧光素酶系统、内源激素含量测定及转录组测序分析，初步明确IbERF4可以直接与DRE元件结合负向调控胁迫响应和氧化应激相关基因表达而调控甘薯耐盐性；但在甘薯抗病性调控中则相对复杂，IbERF4与GCC-Box元件之间并没有直接作用关系，且不影响甘薯中乙烯合成以及茉莉酸信号途径相关基因表达，而苯丙氨酸代谢途径部分基因上调，推测IbERF4可能通过调控苯丙氨酸代谢途径而参与甘薯抗病反应，具体机制仍在研究中。本研究明确了IbERF4在甘薯胁迫响应中的功能并初步阐明了其作用机理，为进一步揭示甘薯抗逆机制及育种利用奠定了基础。