Functional Analysis and Identification of the Pathogenicity-Related Genes and Mating-Type Genes in Rice Blast Fungi, Magnaporthe grisea.

从我们构建的稻瘟菌附着胞形成期差异cDNA文库中，通过DNA宏阵列和RT-PCR方法筛选出一些在附着胞形成期和/或侵染早期强表达的致病性/毒性相关基因的候选克隆。在这些基因中，我们选择了3个基因，FMI 1（Magnaporthe Infection 1的功能基因;克隆#B19）、FMI 2（克隆#B48）和MGH 61 A（Magnaporthe Glycoside Hydrase家族61 A;克隆#B59），它们在早期感染阶段更特异性地表达。对这些基因和基因组结构进行了详细的分析，并通过同源重组产生了基因破坏突变体，以阐明潜在的生理功能。FMI 1基因编码富含丝氨酸的部分序列和定位于细胞核的信号肽的氨基酸序列的N-末端，以及与蔗糖酶/铁氧还蛋白的部分同源序列， ...更多信息 C端。FMI 2基因编码与双特异性磷酸酶同源的活性结构域的一部分。FMI 1和FMI 2基因被破坏的突变体在侵染初期表现为附着胞的异常形成和侵染的延迟，但其影响有限，并被可见的病斑形成所克服。MGH 61 A基因是一个分泌型蛋白，其5 '端编码与糖苷酶家族61高度同源的序列域，并带有一个信号肽。在世界范围内收集了许多稻瘟病菌菌株，主要来自越南，以检测致病小种和自然杂交能力。除中国云南和美国的标准菌株外，没有发现具有高杂交能力的菌株，但在我们收集的菌株中发现了多种致病小种。有趣的是，在越南分离株中发现了一种非常新颖和独特的双链RNA病毒。RNA病毒易感染另一健康分离株，使其生长和毒力下降。少

From our differential cDNA library of Magnaporthe grisea at appressorium formation constructed by subtracting cDNA clones expressing in mycelial growth, some candidates clones were selected by the DNA macro array and the RT-PCR methods as the pathogenicity/virulence-related genes strongly expressed at appressorium formation and/or early infection stage. Of the genes, we selected 3 genes, FMI1 (Functional gene of Magnaporthe Infection 1 ; clone #B19), FMI2 (clone #B48) and MGH61A (Magnaporthe Glycoside Hydrase family 61A ; clone #B59), which were more specifically expressed during early infection stage. These gene and genomic structures were analyzed in detail and also the gene-destructed mutants were created by homologous recombination to elucidate the potential physiological functions. The FMI1 gene encoded the serine-rich partial sequence and a signal peptide to localize in nucleus at N-terminus of the amino acid sequence, and also partial homologous sequence to sucrase/ferredoxin at … More the C-terminus. The FMI2 gene encoded a part of the active domain homologous to dual specificity phosphatase. The FMI1 and FMI2 genes-destructed mutants abnormally formed appressoria and delayed in infection, although their affects were limited during early infection stage and overcome by the visible lesion formation. The MGH61A gene provably was a secreted-type protein with a signal peptide, encoding highly homologous sequence domain to glycoside hydrase family 61 at 5'-end. The gene-destructed mutants descended significantly in appressorium formation, infection and lesion formation.Many isolates of Magnaporthe grisea were collected worldwide, mainly from Vietnam, to check the pathogenic race and natural crossing ability. Except the standard isolates found in Yunnan in China and made in USA, no isolate having high ability to cross was found, although many kinds of pathogenic races were found in our collections. Interestingly a very novel and unique double strands RNA virus was found in Vietnam isolates. The RNA virus easily infected to another healthy isolate and caused to decline the growth and virulence. Less