【作者】 刘路宁；

【导师】 董金皋；

【作者基本信息】 河北农业大学 ， 植物病理学， 2004， 硕士

【摘要】 玉米大斑病是玉米生产上的一种重要叶部病害。其病原菌的无性态为Exserohilum turcicum(Pass.)Leonard et Suggs，有性态为Setosphaeria turcica。大量研究表明，该病菌产生的致病毒素(HT-毒素)，是其致病的主要原因。玉米大斑病菌是异宗配合真菌，有性杂交可能会增强其致病力。通过对有性杂交后代生物学性状以及寄生适合度和产毒能力的深入了解，对控制其潜在危害具有重要意义。 本试验通过对产孢量和菌丝生长速度的测定，研究了玉米大斑病菌有性杂交后代的生物学特性。发现后代菌株相互之间以及亲代与后代菌株之间在菌丝生长速率和产孢量上存在差异。后代菌株与亲代菌株在部分生物学性状上出现了性状分离，其性状分离比为27.4％。 对有性杂交后代的寄生适合度研究后发现，有性杂交后代在寄生适合度上有显著的差别。一些后代菌株能在感病寄主上形成较大型的病斑，产孢量相对也很大，属强寄生适合度类型，而另一些菌株不能诱导感病寄主发病。可见，通过有性杂交可以形成寄生适合度强的菌株，也会形成寄生适合度弱的菌株，也可能使一些后代菌株失去寄生能力。 利用离体叶片针刺法，对后代菌株所产毒素的活性进行了测定。发现后代菌株的粗毒素对供试玉米品种均表现出了一定程度的毒性。不同菌株所产之间毒素所致病斑面积不同，说明不同菌株产生的毒素致毒活性不同。另外，生测结果还显示，1／3后代菌株的粗毒素，在带有不同单抗性基因的玉米叶片上，没有表现出活性的差异，2／3的后代菌株的毒素在带有不同单抗性基因的玉米叶片上表现出致毒活性分化的现象。 对高效液相色谱(HPLC)技术分离毒素组分的最佳条件进行了摸索。试验表明，用50％甲醇与50％的超纯水作流动相，可以将毒素各组分较好的分离开来。进样量为15μL时检出峰的数量最多。加入不同浓度的酸试剂(乙酸)对毒素的分离影响很大。但经过比较，不加酸试剂比加入酸试剂的分离效果好。按上述优化条件对亲代及后代菌株的毒素进行HPLC分析，发现后代菌株毒素之间既存在相同的组分又存在不同的组分。后代菌株毒素与两个亲本菌株毒素之间既存在某些相同的组分，又存在不同的组分。两个亲代菌株毒素的某些组分是不同的，后代毒素的组分有的与亲本01-12的某些或某个组分相同，有的与亲本01-15的某些或某个组分相同。另外，后代毒素中还存在两个亲本毒素所不具有的组分。更多还原

【Abstract】 Northern Leaf Blight of Corn (NLBC) is a major leaf disease of corn. The causual agent is Exserohilum turcicum. Setosphaeria turcica is its sexual stage. The former reseaches indicated that the pathotoxin named HT-toxin produced by its fungal pathology was the important reason causing this disease. The Setosphaeria turcica was sexual stage of this fungal pathogen.The genetic variation of some biological characteristics including pathogenicity and toxigenicity in the ascospore cultured progenies of isolate 01-12 and 01-15 of Setosphaeria turcica was analyzed in this paper. The results revealed that the character of some progenies was significantly different from their parent isolates and sister isolates in the growth velocity and the amount of conidium. when they were cultured in the PDA medium.There were significant differences among the progenies of sexual hybridization in infection efficiency,latent period,lesion size,sporulation and fitness index. Some progenies with strong fitness index or weak fitness index emerged. Through the research we found that the progenies of sexual hybridization of this fungal pathogen have higher or lower fitness index than its parent isolates.The biological activity of progeny isolate toxins were analyzed using acupuncturing leaves in vitro manifested that they had different toxicity to corn. The lesion areas on inhomogeneous species of corn produced by the toxins of some progenies were different. This kind of toxin occupied one third of the total toxins. Other two third of the total toxin did not manifest difference among the inhomogeneous species of corn.The best isolating conditions for the toxins of the progenies had been studied using high performance liquid chromatography(HPLC). The results were as follows:50%methanol and 50% hyperpure water could be used as mobile phase to isolate the toxin of the progenies. Add acid reagent had largely effect on separating degree of the toxin. The quantity of peak was the bigest when the injection quantity was 15 uL.The experiment manifest the toxin could be isolate effectively with noacid reagent added. The peak had good separating degree in the condition. We foundthe toxin of the progenies was different they had same fractions and dissimilarfractions. The some fractions of progeny isolate toxins were same with the fractionof the toxin of their parents,some did not exist in the toxin of their parents.更多还原