拮抗木霉菌疏水蛋白Hyd1诱导玉米抗全株病害内生微生物组学机理

Application of Trichoderma biological control agent (BCA) is crucial way to realize systemic control of maize soilborne and airborne diseases(foliar diseases). Previous study showed that the interaction of elicitor of T.harzianum,hydrophobin1（Hyd1）and its specific responsive protein,ubiquilin1-like(UBQLN1-like) is able to trigger maize systemic immunity response against stalk rot and foliar diseases,however,it is unclear how much contribution of induced endophytic microbiome to the evolution of Trichoderma-induced whole plant immunity response.In this study with maize stalk rot (Fusarium graminearum )and northern leaf blight (Exserohilum turcicum)as target diseases, we are going to work on effects of Trichoderma secreted hyd1, maize root responsive protein, UBQNL1-like and both molecular interaction on diversity and abundance of endophytic microbiome，quorum-sensing signal expression ,the concentration of siderphore,ABA,IAA in order to confirm their correlation with induced systemic resistance to pathogen infection and corresponding decline of Fusarium toxin (DON,NIV,ZEA) in maize plant organs(seed、root,stem and leaf) and tissues (endodermis, phloem and xylem etc.) at seedling and adult stage. The change of specific endophytic microbiome induced byHyd1-UBQLN1-like was further investigated on its correlation with systemic resistance induction and toxin decline.Morevoer,the vertical transfer of specific beneficial endophytes between host organs and its influence on the hyd1-UBQNL1-like interaction, host defense gene expression as well as signals（BR、JA/ET、Ca2+、ROS etc.）long distance transduction is comprehensively revealed so as to ensure how much devotion of those beneficial endophytes to whole plant resistance against stalk rot and northern leaf blight. Taken together, a Trichoderma elicitor hyd1 interaction with maize root responding protein UBQLN1-like is viewed as a driver leading to systemically induced maize endophytic microbiome changes which thus strongly devote to Trichoderma induced-systemic control of whole plant diseases. The study will be first report from endophytic microbiomics point of view to give an new insight on a well known model of microbe associated molecular patterns (MAMPs) underlining Trichoderma -stimulated maize immunity against whole plant diseases.

生防木霉菌菌剂处理土壤或种子诱导玉米全株免疫反应是实现土传病害和气传病害系统防控的重要途径。前期研究表明，哈茨木霉菌激发子疏水蛋白Hyd1与玉米根系特异响应蛋白类泛醌蛋白1UBQLN1-liket互作能够诱导玉米抗茎腐病和叶斑病的系统免疫反应，但不清楚这种全株免疫反应的形成是否与植株内生微生物组的变化存在因果关系。本项目以镰孢菌茎腐病和大斑病为靶标，研究Hyd11-UBQLN1-like互作对玉米不同器官、细胞组织内生微生物组多样性和丰富度、群体感应信号、生长激素、拮抗性物质的影响，明确特异响应内生微生物组变化与系统诱导抗性和减毒素效应的关系；研究特异响应有益内生微生物在玉米器官间转运与玉米防御反应信号长距离转导和抗性的相关性，明确Hyd1-UBQLN1-like互作诱导的玉米内生微生物组变化对全株抗病性形成的贡献水平。首次提出木霉菌Hyd1系统诱导玉米抗全株性病害内生微生物组学机理。

木霉诱导玉米系统抗病性分子机制与内生微生物组密切相关，国内外尚无系统研究。本研究通过内生微生物组分析等方法，重点开展了哈茨木霉（Trichoderma harzianum）T28疏水蛋白hyd1诱导玉米的靶标-类泛醌蛋白（ubiquilin1-like)调控内生微生物组变化及对根腐病和大斑病抗性的影响机制。主要进展：⑴木霉hyd1能促进玉米植株生长，提高玉米对镰孢菌根腐病的抗性；⑵哈茨木霉菌株T28处理的玉米中的内生菌-戴沃斯菌属和凯斯特亚菌属相对丰度最高，而hyd1敲除株和其过表达株处理中两属相对丰度减少,说明hyd1基因表达对玉米内生菌的影响存在剂量效应；⑶响应木霉hyd1诱导作用的玉米ubiquilin1-like能促进玉米的生长并减少病原菌侵染的死亡率，玉米ubiquilin1-like过表达株中的自然混合菌群能显著抑制大斑病菌和拟轮枝镰孢菌生长；⑷木霉诱导茎基节、茎中节及穗下茎节内生真菌 Chao 1 丰富度估计指数分别升高 42.15%、6.73%和 5.21%，内生细菌 Chao1 丰富度指数分别升高99.30%、29.44%和 24.60%，增加水平由下至上逐步递减，说明距离诱导源越近，诱导效应越明显。玉米Ubiquilin1-like没有明显改变叶片内生微生物的群落多样性，但内生细菌胃球菌属、普雷沃氏菌属、真杆菌属和消化球菌属可能与ubiquilin1-like调控的抗性作用有关。发现木霉诱导的内生微生物主要种群对茎基部脱氧雪腐镰刀烯醇(deoxynivalenol, DON)和玉米赤霉烯酮（Zearalenone, ZEN）含量分别下降 52.88%和 21.08%；⑸hyd1调控木霉诱导玉米抗镰孢菌的防御反应JA/ET途径相关基因LOX1、OPR7等的表达量均明显上调。由此，提出木霉hyd1和ubiquilin1-like诱导玉米内生微生物组对镰孢菌根腐病和大斑病抗性作用的微生态学机理。