Molecular Genetic Analysis of the Rice Blast Fungus, Magnaporthe Grisea

Valent, Barbara; Chumley, Forrest G.

doi:10.1146/annurev.py.29.090191.002303

Cited by 322 publications

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“…Outbreaks of rice blast disease are a serious and recurrent problem in all rice-growing regions of the world, and the disease is extremely difficult to control 1,2 . Rice blast, caused by the fungus Magnaporthe grisea, is therefore a significant economic and humanitarian problem.…”

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The genome sequence of the rice blast fungus Magnaporthe grisea

Dean

Talbot

Ebbole

et al. 2005

Nature

1,486

1,194

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Magnaporthe grisea is the most destructive pathogen of rice worldwide and the principal model organism for elucidating the molecular basis of fungal disease of plants. Here, we report the draft sequence of the M. grisea genome. Analysis of the gene set provides an insight into the adaptations required by a fungus to cause disease. The genome encodes a large and diverse set of secreted proteins, including those defined by unusual carbohydrate-binding domains. This fungus also possesses an expanded family of G-protein-coupled receptors, several new virulence-associated genes and large suites of enzymes involved in secondary metabolism. Consistent with a role in fungal pathogenesis, the expression of several of these genes is upregulated during the early stages of infection-related development. The M. grisea genome has been subject to invasion and proliferation of active transposable elements, reflecting the clonal nature of this fungus imposed by widespread rice cultivation.Outbreaks of rice blast disease are a serious and recurrent problem in all rice-growing regions of the world, and the disease is extremely difficult to control 1,2 . Rice blast, caused by the fungus Magnaporthe grisea, is therefore a significant economic and humanitarian problem. It is estimated that each year enough rice is destroyed by rice blast disease to feed 60 million people 3 . The life cycle of the rice blast fungus is shown in Fig. 1. Infections occur when fungal spores land and attach themselves to leaves using a special adhesive released from the tip of each spore 4 . The germinating spore develops an appressorium-a specialized infection cell-which generates enormous turgor pressure (up to 8 MPa) that ruptures the leaf cuticle, allowing invasion of the underlying leaf tissue 5,6 . Subsequent colonization of the leaf produces disease lesions from which the fungus sporulates and spreads to new plants. When rice blast infects young rice seedlings, whole plants often die, whereas spread of the disease to the stems, nodes or panicle of older plants results in nearly total loss of the rice grain 2 . Different host-limited forms of M. grisea also infect a broad range of grass species including wheat, barley and millet. Recent reports have shown that the fungus has the capacity to infect plant roots 7 .Here we present our preliminary analysis of the draft genome sequence of M. grisea, which has emerged as a model system for understanding plant-microbe interactions because of both its economic significance and genetic tractability 1,2 . Acquisition of the M. grisea genome sequenceThe genome of a rice pathogenic strain of M. grisea, 70-15, was sequenced through a whole-genome shotgun approach. In all, greater than sevenfold sequence coverage was produced, and a summary of the principal genome sequence data is provided in Table 1 and Supplementary Table S1. The draft genome sequence consists of 2,273 sequence contigs longer than 2 kilobases (kb), ordered and orientated within 159 scaffolds. The total length of all sequence contigs is 38.8 mega...

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mentioning

confidence: 99%

“…Here we present our preliminary analysis of the draft genome sequence of M. grisea, which has emerged as a model system for understanding plant-microbe interactions because of both its economic significance and genetic tractability 1,2 .…”

mentioning

confidence: 99%

The genome sequence of the rice blast fungus Magnaporthe grisea

Dean

Talbot

Ebbole

et al. 2005

Nature

1,486

1,194

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“…Light microscopic investigation of the B-karyotype and the PFGE data clearly show seven chromosomes, indicating that there is no dispensable or supernumerary chromosome (Figs 1 and 2). The existence of small supernumerary chromosomes that lead to variation in the genome size has been shown for several plant pathogenic ascomycetes and for Aspergillus nidulans (Miao et al, 1991;Valent & Chumley, 1991;Tzeng et al, 1992;Geiser et al, 1996). Therefore, the differences in the S. macrospora genome size may result either from deletions or additions of chromosomal sequences, or from imprecise size estimations based on comparisons of separated chromosomes with those of S. pombe.…”

Section: Discussionmentioning

confidence: 99%

Karyotype polymorphism correlates with intraspecific infertility in the homothallic ascomycete Sordaria macrospora

Pöggeler¹,

Masloff²,

Jacobsen³

et al. 2000

Journal of Evolutionary Biology

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The homothallic fungus Sordaria macrospora produces perithecia with meiotically derived ascospores. In most cases, intraspecies crosses between strains from different culture collections generate fertile hybrid perithecia in the contact zone of two mycelia. However, in some of these crosses we observed a significant decrease in the fertility of the hybrid perithecia when strains of different origin were used for mating. Since we assumed that chromosome variability between the culture collection strains might contribute to this reduction in fertility, we performed pulsed‐field gel electrophoresis. In the course of our study, we were able to identify two major groups of electrophoretic karyotypes in S. macrospora culture collection strains. A quantitative analysis revealed that polymorphic karyotypes contribute to a reduction of fertility in forced crosses between strains carrying differently sized chromosomes. The observed intraspecific chromosome length polymorphism might have consequences on the speciation process of a homothallic fungus capable of sexual but not of asexual spore formation.

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“…Initially biotechnology was applied in rice blast research for detection purpose using RFLP (Hamer, Farrall, Orbach, Valent, & Chumley, 1989). Then the studies on genome organization and molecular analysis of blast fungus taken step forward (Valent & Chumley, 1991). The further research explored the mechanism of host pathogen interaction at molecular level involving MAP kinase and cAMP signaling pathways (Xu & Hamer, 1996).…”

Section: Biotechnological Approachesmentioning

confidence: 99%

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2014

Plant Sci Today

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Blast disease caused by fungal pathogen Magnaporthe oryzae is the most severe disease of rice (Oryza sativa L). On an estimate it annually destroys rice, which can feed around 60 million people. Keeping in view the importance of the disease, various management strategies like controlled use of nitrogen fertilizers, application of silica and flooding of paddy fields are the practices in use to reduce the rice blast since long time. Improved chemical methods include utilization of copper fungicides, organomercuric and organophosphorus compounds. Some antibiotics e.g., Blasticidin S and Kasugamycin and many systemic and site specific fungicides including melanin biosynthesis inhibitors and plant activators were also utilized effectively for blast management. In the recent years leaf extracts of tulsi and bael have been found effective. Due to the highly variable nature of M. oryzae, exploitation of durable host resistance has remained a challenging job for plant pathologists and breeders. Lots of efforts have been made worldwide to study the variability in the pathogen and to find out the resistance sources. To date approximately 100 R genes for blast resistance have been mapped and 20 of these genes have been cloned in rice. Now, scientists are looking forward to develop durable resistant varieties through pyramiding of quantitative trait loci and major genes. Among the biocontrol agents, different strains of Bacillus spp. and Streptomyces sindeneusis are in use. The availability of rice and M. oryzae genome sequence data are facilitating blast resistance management program to new paradigms which includes isolation and characterization of R and Avr genes, development of noble fungicides, transformed bioagents, transgenic rice and durable resistance.

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Molecular Genetic Analysis of the Rice Blast Fungus, Magnaporthe Grisea

Cited by 322 publications

References 38 publications

The genome sequence of the rice blast fungus Magnaporthe grisea

The genome sequence of the rice blast fungus Magnaporthe grisea

Karyotype polymorphism correlates with intraspecific infertility in the homothallic ascomycete Sordaria macrospora

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