尖角突脐胞菌附着胞形成的影响因子研究

The fungus Exserohilium monoseras that depends on its appressorium formation in the infecting process is a potential biocontrol agent for barnyardgrass Echinochloa crusgalli. E. monoseras (Drechsler) Leonard and Suggs strain X27 was isolated by the Weed Science Laboratory of South China Agricultural University, Guangzhou, China in our previous study. In the present study, considered it as the study material, various influence factors affecting the appressorium formation of E. monoceras will be investigated in the leaves of rice and barnyard grass, from the blade surface strucure, the physiological and biochemical substances to the cAMP signal transduction pathways. The differences in effects of these factors on in the leaves of rice and barnyard grass will be also studied comparatively. Which will clarify the infecting pathway and the influence factors of E. monoseras appressorium formation, and explore the methods of increasing appressorium formation in quantity. Furthermore, the reason of no E. monoseras appressorium formation in rice under infecting process will be determined. The results are to reveal the biocontrol mechanisms of E. monoceras, which will provide important theory significance on choosing available factors that could improve the efficiency of E. Monoseras as herbicide and its application on the field.

尖角突脐孢菌能够生物防除稗草的根本原因是在侵染的过程中有附着胞的形成。利用已经筛选到的具有开发成真菌除稗剂潜力的稗草强致病菌—尖角突脐孢菌，从叶片表面结构，生理生化物质，cAMP信号传导途径三个方面对尖角突脐胞菌附着胞形成的各种影响因子进行详细研究，对比分析各因子在水稻和稗草叶片上的影响变化，确定尖角突脐胞菌附着胞形成的侵染途径及影响因子，探明提高附着胞产生量的方法，明确尖角突脐孢菌侵染水稻时附着胞不能形成的原因。其结果将揭示尖角突脐胞菌的生物防除机制，对筛选提高尖角突脐胞菌生物农药效率的因子和该菌的杀草作用及田间应用具有重要的理论意义。

尖角突脐孢菌能够生物防除稗草的根本原因是在侵染的过程中有附着胞的形成。利用已经筛选到的具有开发成真菌除稗剂潜力的稗草强致病菌—尖角突脐孢菌，从叶片表面结构，生理生化方面，cAMP信号传导途径三个方面对尖角突脐胞菌附着胞形成的各种影响因子进行了详细研究，主要取得了如下研究成果：（1）稗草及水稻叶片表面蜡质中差异显著的初级醇类，烷烃类及醛类物质是影响尖角突脐孢菌附着胞形成的主要原因，非寄主植物水稻叶片表面蜡质对尖角突脐孢菌附着胞形成有抑制作用，寄主植物叶片表面蜡质对其附着胞形成有促进作用。（2）培养基硬度影响尖角突脐孢菌菌落的生长，在较硬及超硬的PDA培养基上尖角突脐孢菌的产孢量和分生孢子的萌发率增加。（3）通过紫外诱变并筛选出对稗草高致病力的尖角突脐孢菌诱变菌株X27-UV148、X27-UV286、X27-UV048、X27-UV045，相对于出发菌株X27来说，诱变株对低温、高温的耐受能力均增强。这4株诱变菌株和出发菌株都对寄主专一，对水稻等8种作物安全，防除稗草时，均能起到较好的防治效果。（4）Ca2+通道抑制剂EGTA和verapamil均会影响尖角突脐孢菌的生长，降低尖角突脐孢菌孢子的萌发率及附着孢的形成，并随着抑制剂浓度的增加，抑制效果增加，且Verapamil的抑制效果比EGTA的高。. 另外，课题组从稻田中的千金子感病植株上分离得到了致病菌，通过生物学鉴定其为嘴突凸脐蠕孢菌，并研究了致病力最强的菌株Y9511作为微生物除草剂的潜力，利用化学（EMS）诱变技术，筛选获得寄主范围专一、遗传稳定和致病力强的诱变菌株Y9511-X050，完成了其对千金子的室内防效及对水稻安全性的测定。尖角突脐孢菌和嘴突凸脐蠕孢菌均可为新型除草剂的研发和应用提供理论基础。