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Chlorimuronethyl resistance geneis increasingly used as a selectable marker for transformation, especially fungal transformation. Magnaporthe grisea is an important model organism for investigating fungal pathogenicity, and Agrobacterium tumefaciens-mediated transformation (ATMT) is used for functional mutagenesis of the fungus. However, our results showed that rice blast strains collected from infectious rice fields have highly conserved resistance to chlorimuronethyl, even comparable to transformants which carrying chlorimuronethyl resistance genes as selectable marker in laboratory conditions. PCR results showed that all tested field strains presented the amplified products of the same size as the selectable marker amplified from plasmid carrying chlorimuronethyl gene. Sequence analysis of PCR products amplified from field strains confirmed that field strains harbored the highly identity homolog of chlorimuronethyl resistance gene. Blast search in GenBank suggested that the fragment is presenting in reference genome sequence of 70-15, but it is not a wide-spread gene in other organisms, excepted for Herpetosiphon aurantiacus. Although the origin and reason of the conserved chlorimuronethyl resistance gene in field isolates of blast fungus is unclear, the ecological function of the gene is noteworthy. [ABSTRACT FROM AUTHOR]

Plant cell walls are a pivotal battleground between microbial pathogens and their plant hosts. Microbial pathogens secrete an array of cell-wall-degrading enzymes to depolymerize the noncellulosic polysaccharides of primary cell walls, which are essential for the vitality of pathogens, either saprophytically, pathogenetically or both. The predicted protein encoded by MGG_01403.5 from Magnaporthe grisea has a high degree of sequence identity with the ferulic acid esterase A (so to be designated as MgFaeA) from Penicillium funiculosum. Tested by the SignalP, TMHMM and Protcomp programs, the 284-amino acid hypothetical protein contained a cleavable signal peptide at the N terminus, lacked transmembrane structure, and appeared located in the extracellular matrix. In the work presented here, MgFaeA, with a His6 tag at its C-terminus, was introduced into M. grisea for overexpression. The MgFaeA-His6 fusion protein was purified from the culture filtrate, which confirmed the secretion property of MgFaeA in the fungus. To further investigate the role of MgFaeA on rice infection, RT-PCR was used to analyze the gene expression during different stages of infection. The results indicated that MgFaeA transcripts were detectable as early as 72 hpi, and reached to peak at 7 dpi. It suggested that the MgFaeA gene might be involved in the fungal pathogenesis. [ABSTRACT FROM AUTHOR]

Laccase is found to be involved in pathogenicity of Cryphonectria parasitica and Cryptococcus neoformans. In this report we demonstrate that laccase is not necessary for pathogenicity in Magnaporthe grisea, which might be due to functional redundancy in some or all of the laccase genes. The major laccase activity in M. grisea is not encoded by either of the MGG_00551.5 and MGG_02876.5 genes, because targeted deletion of each gene shows only a slight decrease in laccase activity compared to wild-type strains. The MGG_00551.5 and MGG_02876.5 mutants share the same growth rate, conidiation and pathogenicity as wild-type strains. Taken together, our findings provide evidence that these genes are not essential for the differentiation and development of M. grisea. [ABSTRACT FROM AUTHOR]

Chinese national differential varieties have failed to provide clues in virulence changes for the two re-surges of rice blast disease causing severe losses in Sichuan of China since 1986, where hybrid rice has been the major crop since 1980. So Lijiang Xintuan Heigu (LTH) and 5 restorer lines as resistance donors of hybrid rice, IR24, Minhui 63 (MH63), Duohui No 1 (DH1), Chenghui 448 (CH448), Neihui 99-14 (99-14) and RHR-1, were used as local differential varieties. In 2005–2006, 243 isolates of Magnaporthe grisea were differentiated into 41 virulent types, of which, 18 were of an annual frequency higher than 2.0% and then respectively named as local physiologic races CB0-CB17. A higher differentiation ability of Sichuan differentials than that of national ones but no distinct links between the races differentiated by two sets of differentials were observed. Based on the virulence spectrums of individual local races and the history of sequential release and breakdown of resistance in the restorer lines, the evolution of virulence of M. grisea in Sichuan was briefly described. Local races virulent to hybrid rice evolved from avirulent race CB0 and successively acquired their virulence to IR24, MH63, DH1, CH448 or (/and) 99-14. All of the races virulent to DH1, CH448, 99-14 and RHR-1 evolved from races virulent to MH63 but virulence to IR24, DH1, CH448 and 99-14 could be bypassed during the evolution. In 2006, the total frequency of CB5, CB14, CB16 and CB17, each virulent to DH1 and over 80 tested hybrid rice, reached 20.3%, which indicated a possible turn for the worse of the blast disease epidemic. [ABSTRACT FROM AUTHOR]

The Magnaporthe grisea Oryza sativa interaction database (www. mgosdb.org) is a web-based repository for Oryza sativa and Magnaporthe oryzae genomic and experimental data with a particular emphasis on host-pathogen interactions. MGOS has recently been enhance to include community annotation and enhanced microarray functionality. The new community annotation functionality allows M. oryzae researchers to document the M. Oryzae transcriptome including: gene name/symbol and description, associated gene ontology and fungal anatomy terms, mutants and associated images, related publications, and transcript information including exon positions and translational start and stop positions. The enhanced microarray functionality allows users to enter all of the data associated with a microarray experiment that is necessary to interpret the results of the experiment. This includes the raw data files for each hybridization, the final processed data set for all hybridizations, the essential sample information (in particular the experimental factors and their values), the experimental design and hybridization scheme, and protocol information. In addition, a community forum system and a literature citation section have been added to the MGOS website. [ABSTRACT FROM AUTHOR]

Eighteen polymorphic microsatellite markers suitable for population genetic studies and protein kinase encoding genic variation measurement were developed for rice blast fungus Magnaporthe grisea. Polymorphism was evaluated by using 46 isolates collected from diverse geographical locations and rice varieties. Preliminary results indicate that each locus harbors two to fourteen alleles. [ABSTRACT FROM AUTHOR]

Thirteen polyporphic microsatellite markers suitable for population genetic structure analysis and ABC transporter and signal transduction coding genes variation measurement were developed for rice blast fungus, Magnaporthe grisea. Polymorphism was evaluated by using forty-six isolates collected from diverse geographical locations and rice varieties. Preliminary results indicated that each locus resolved multiple alleles ranging from two to ten. There results showed that these SSR-containing genes are also polymorphic in the natural population. [ABSTRACT FROM AUTHOR]