【作者】 刘彬；

【导师】 黄云； 何忠全；

【作者基本信息】 四川农业大学 ， 植物病理学， 2007， 硕士

【摘要】 稻瘟病菌(Magnaporthe grisea)引起的水稻稻瘟病是流行最广危害最大的世界性真菌病害之一。目前，防治稻瘟病最经济有效的方法是培育和利用抗病品种，并对抗病品种进行合理布局。但是，抗病品种往往在田间推广3～5年或者更短时间内就“丧失”抗性。抗性的“丧失”与病原菌致病性的变异及水稻品种的专化抗性有关。本文对四川稻瘟病菌的稳定鉴别菌株的筛选进行了初步研究，实验结果如下：1．用中国鉴别品种、日本清泽粳型单基因系鉴别品种、国际水稻所C039籼型近等基因系鉴别品种对105个四川稻瘟病菌株进行鉴定，结果表明：(1)中国鉴别品种将105个菌株划分为7群18个小种；(2)C039NILs鉴别品种将105个菌株被分成19个小种，优势小种明显；(3)日本清泽单基因系鉴别品种将105个菌株被划分成103个小种，生理小种划分作用明显；(4)聚类分析表明，中国鉴别品种划分的小种致病型与其它2套鉴别品种划分的种群比较，不存在一一对应的关系。2．从供试的105个菌株中，筛选了20个产孢量好、致病力强的菌株进行了继代培养。在中国鉴别品种上经致病性测定后，多数菌株生理小种的种群没有改变，但生理小种出现了变异。这20个强致病菌系的致病性不稳定，其毒力在继代过程中有逐渐弱化的趋势。多数菌系的继代菌株在日本清泽粳型单基因系鉴别品种上的致病型变化大，无毒基因有明显的改变，原来无毒的基因在继代时可以变为毒性基因，原来的毒性基因也可以变为无毒基因；仅有少数菌系的前面几代或中间几代菌株的无毒基因没有发生变化。说明多数菌株所含有的无毒基因随着继代培养都不同程度的发生了变异。3．经致病性测定后，筛选出10个致病性相对稳定的菌系，进行生物学特性测定和分子检测。多数菌系内的继代菌株在不同的温度作用下，菌丝平均生长速度没有明显的差异，随着菌株继代培养的代数增加，菌丝的产孢作用减弱；各代菌株的菌丝平均生长速度在不同pH值下，差异不明显；随着菌株继代培养的代数增加，生长有减弱的趋势，产孢量有明显的变化，后面几代的产孢量明显少于前面几代；不同光照处理对菌系的各继代菌株的菌丝生长影响不明显，各继代菌株间在不同的光照处理条件下，产孢量有明显差异。在分子生物学方面，供试菌株在不同的相似水平下可被划分为不同的遗传宗亲群。多数菌系在继代过程中，菌株间的遗传多样性差异小，相对稳定；同时随着继代菌株致病性的减弱，菌株的变异趋于稳定；少数菌系在继代过程中，发生了较大的变异，且多数菌株的生理小种与宗亲群没有简单的一一对应关系。更多还原

【Abstract】 The rice blast caused by Magnaporthe grisea was one of the epipHyte disease of the most prevailed-wide and big-damaged. Now the best ways of economical and efficient to prevent rice blast is to make use of resisted breeds and make them distribution with reason. When these breeds were been put into use in 3～5years or less time, the fastness of breeds will lose. The reason is that rice blast pathogenicity and special fastness of rice breeds have changed. This passage is about studying on steady differential fungus strains of rice blast in Sichuan. The results are as followes:1. The 105 isolates collected from rice in Sichuan were studied with three sets of differentials. The Chinese race differentials, the CO39 near isogenic lines, the Tsunematru mono-resistance gene lines from Japan could differentiate 105 isolates into 7,19 and 103 pathogenic types respectively. The Tsunematru mono-resistance gene lines from Japan had a evident differentiating ability. Cluster analysis showed that compared with Chinese race differentials, there was no distinctive correlation with pathogenic types.2. From the 105 isolates, we choosed 20 isolates that had good conidia and strong pathog enic ability. With the Chinese race differentials, lots of the population of cultivating subcultu re M.grisea did not change, but the race of M.grisea isolates to some extent had transformed during cultivating subculture M.grisea isolates. The strong pathogenic ability was instability. Virulence of M.grisea gradually died away in the course of cultivating subculture M.grisea isolates. The pathogenic types of most subculture M.griseaisolates of strains had evidently changed on the Tsunematru mono-resistance gene lines from Japan, whose innocuous genes comed forth obviously change. The genes between innocuity and virulence could transforme each other. The innocuous genes of few subculture M.grisea isolates of strains did not vary. So with cultivating subculture, the innocuous genes of most isolates had chaged in different degree.3. After pathogenicity detection, we chosed 10 strains whose pathogenicity was relatively steady to detect biological characteristic and molecule detection. In different temperature, the average speed of mycelial growth of subculture M.grisea did not happen clear change. With cultivatin g subculture, the ability of producing conidia becomed to weaken; In different pH, the average speed of mycelial growth of subculture M.grisea also did not happen clear change, but the growth had imperfect current. The number of conidia happened distinctly transformation and the number of conidia of the later was less than the front; The average speed of mycelial growth of subculture M.grisea was not obviously effected by different illumination and the number of conidia had great change. At molecule detection, the isolates could be divided into different genetic lineages in different resemble lev el. During cultivating subculture, the genetic diversity between subculture M.grisea had little diff erence. With the pathogenicity weakening, the variance of isolates becomed steady; Few strains happend biggish variance, there was no distinctive correlation betwwen pathogenic types and genetic lineages.更多还原