【作者】 周晓云；

【导师】 王克荣；

【作者基本信息】 南京农业大学 ， 植物病理学， 2001， 硕士

【摘要】 本研究通过菌株的突变体生理表型互补试验、有性杂交、异核体及RAPD分析等方法，对串珠镰孢霉含钼协同因子基因位点、含钼协同因子与亚硝酸盐还原酶基因间的相互关系、异核体的遗传稳定性、形成色素能力及其遗传，以及不同寄主和地区来源的菌株间群体结构等方面进行研究。 根据对单孢菌株的42个含钼协同因子缺陷型突变体（nitB）互补测定结果，首次测定至少有7个基因位点控制含钼协同因子；硝酸盐还原酶缺陷型突变体（nitA）和亚硝酸盐缺陷型突变体（nitC）各自互补的结果表明，除单基因控制这两种酶的产生外，还存在其他基因的调控；对筛选到的两株主氮调节基因缺陷型突变体（niD）的研究结果也表明，随着该种类型突变体的产生，往往会丧失突变体的雌性可育性能力。 串珠镰孢菌含钼协同因子突变体缺陷型（nitB）与亚硝酸盐还原酶缺陷突变体（nitC）间的杂交结果显示，在不同的交配群以及在相同交配群的不同寄主上的分离菌，控制这两种酶的基因有两种类型。首次提出细胞核基因和细胞质基因共同调控硝酸盐还原途径酶的假说。当杂交后代出现四种表型（nitD：nitB：nitC：wt=1：1：1：1）时，说明这两种酶只受核基因的调控，分离时两种基因自由组合；而当杂交后代仅有两种表型时，表现为父本表型隐藏，主氮调节基因缺陷型（nitD）表型不出现，即母本表现型：野生型=1：1，认为这种遗传情况除了受核基因的控制外，还存在细胞质基因的影响。 对异核体的无性遗传稳定性的研究说明，串珠镰孢霉同一VCG菌株间粗、形成的异核体遗传稳定性较差，一般3～5代即丧失异核体的特征。说明形成异核体和进行准性生殖不是引起串珠镰孢霉群体遗传多样性的主要原因。 菌株产色素的能力无性遗传相对较稳定，根据有性杂交的结果，首次提出由单主效基因控制色素前体的产生，但色素的产生与否还受一定数量的微效基因控制，这些微效基因与色素产生的量以及色素形成的快慢有关。 用9条引物对不同来源的串珠镰孢霉菌株进行RAPD扩增，共产生88个 周晓云 李瑟组镰抱霉的遗传学条带的RAPD汁于标记，其中97．73％具有多态性。根据RAPD谱带计算出的菌株riJ遗传相似性进行聚类分析表明，整个群体的多态性与菌株的寄主和地区来源问不存在相关性。但是分别以寄上和交配群划分的不同群体进行聚类时，A、DFg交配群体仰遗仕差异较小，遗传变异量为0刀348；奇主为水稻和玉米的菌株群体仰退传芹异最人，巡传变疗量为0．24。而且在A、D交配群中，亚议体的划分＼ 术奇k有一定的相关性。更多还原

【Abstract】 Studies on gene loci of molbdcmum containing cotactor, the genetic relationship between molvhdernurn containing cofactor and nitrite reductase, the genetic stability of heterokaryon. the ability of pigment formation and its inheritance, as well as population structure of I2uxuriuni rnonihforrnL?isolated from different hosts and collecting places. were carried out by physiological complementation test, sexual cross, heterokaryon formation and RAPD analysis, respectively.Complernentation analysis of forty-two molybdemum containing cofactor mutants (nitB) obtained from the same strain 慡C5O?revealed that at least seven different genes were involved. Likewise, the results of complementation tests of all nitrate ruductase mutants (nitA) and all nitrite reductase mutants (nitC) obtained from the same strain ~SC50?also revealed that apart from single gene, there were other genes to regulate the two enzymes, nitrate reductase and nitrite reductase. The result of studies on two major nitrogen regulatory loci mutants (nitD) revealed that, with the occurrence of this type of mutants, they often deleted the ability of female fertility.The analysis results of sexual progenies between molybdemum containing cofactor mutants (nitB) and nitrite reductase mutants (nitC) showed that there were two kinds of gene to control the enzymes, molybdernurn containing cofactor and nitrite reductase, in different mating populations and in different hosts in the same mating population of the pathogen. It is the first time to propose the hypothesis that3J~j~nuclear gene and cytogene co-control the enzymes related to nitrate utilization pathway. If the ratio of segregation is 1:1:1:1 to four different phenotypes (nitD,nitB,nitC,wt), they were under the control of nuclear genes; Otherwise, two phenotypes were emerged by female parent phenotype and wild type, with ratio of 1:1, male parent phenotype was disappeared, there were two set of gene (nuclear gene and cytogene) controlled the two enzymes (molybdemum containing cofactor and nitrite reductase).The inheritance of heterokaryon between two isolates which belong to the same vegetative compatibility group (VCG) was unstable, the trait of heterokaryon was disappeared during 3~-~5 generations. These revealed that parasexuality and heterokaryosis were not the main reasons including genetic variation and diversity in F moni1~fornie.The ability to secrete pigment is stable in asexual stage, according to sexual crossing, it is the first time to propose the hypothesis that there were a pair of alleles (A, a) controlling the production of pigment precursor, but the pigment production relied on the presence of a number of numerical trait genes, however, the number of these genes is related to quantity and time of pigment production.Nine primers were used to amplify DNA of F moniljforme isolates in this study. 88 RAPD markers were obtained, 97.73% were polymorphisms. Based on the genetic distance from the result of RAPD fingerprinting showed that polymorphyism of strains were not obviously related to their collected place or hosts. However, system cluster analysis based on hosts and mating populations showed that the difference between A and D mating populations is rather small, the variation being 0.0348; while it抯 more big between strains isolated from rice and maize, the variation being 0.2412. and there was a certain correlation to the host of maize in A, D mating populations.更多还原