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Genome-Wide Analysis of Hypoxia-Responsive Genes in the Rice Blast Fungus, Magnaporthe oryzae.

Choi J, Chung H, Lee GW, Koh SK, Chae SK, Lee YH - PLoS ONE (2015)

Bottom Line: However, such defects did not cause any significant decrease in disease severity.The other mutant, for the alcohol dehydrogenase gene MoADH1, showed no defect in the hypoxia-mimicking condition (using cobalt chloride) and fungal development.Taken together, this comprehensive transcriptional profiling in response to a hypoxic condition with experimental validations would provide new insights into fungal development and pathogenicity in plant pathogenic fungi.

View Article: PubMed Central - PubMed

Affiliation: Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 406-772, Korea.

ABSTRACT
Rice blast fungus, Magnaporthe oryzae, is the most destructive pathogen in the rice-growing area. This fungus has a biotrophic phase early in infection and later switches to a necrotrophic lifestyle. During the biotrophic phase, the fungus competes with its host for nutrients and oxygen. Continuous uptake of oxygen is essential for successful establishment of blast disease of this pathogen. Here, we report transcriptional responses of the fungus to oxygen limitation. Transcriptome analysis using RNA-Seq identified that 1,047 genes were up-regulated in response to hypoxia. Those genes are involved in mycelial development, sterol biosynthesis, and metal ion transport based on hierarchical GO terms, and are well-conserved among three fungal species. In addition, mutants of two hypoxia-responsive genes were generated and their roles in fungal development and pathogenicity tested. The mutant for the sterol regulatory element-binding protein gene, MoSRE1, exhibited increased sensitivity to a hypoxia-mimicking agent, increased conidiation, and delayed invasive growth within host cells, which is suggestive of important roles in fungal development. However, such defects did not cause any significant decrease in disease severity. The other mutant, for the alcohol dehydrogenase gene MoADH1, showed no defect in the hypoxia-mimicking condition (using cobalt chloride) and fungal development. Taken together, this comprehensive transcriptional profiling in response to a hypoxic condition with experimental validations would provide new insights into fungal development and pathogenicity in plant pathogenic fungi.

No MeSH data available.


Related in: MedlinePlus

The steroid biosynthesis pathway in M. oryzae.Intermediates are boxed in white and final products are boxed in black. Genes involved in the pathway are circled. Numbers in the gene names are gene IDs that start with ‘MGG.’ Up-regulated genes are colored in red and down-regulated genes in blue. ‘No significant regulation’ is colored in white.
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pone.0134939.g003: The steroid biosynthesis pathway in M. oryzae.Intermediates are boxed in white and final products are boxed in black. Genes involved in the pathway are circled. Numbers in the gene names are gene IDs that start with ‘MGG.’ Up-regulated genes are colored in red and down-regulated genes in blue. ‘No significant regulation’ is colored in white.

Mentions: Gene Ontology (GO) enrichment analysis was conducted to understand functions of genes influenced by hypoxia. The R package ‘topGO’ was used to identify GO terms enriched in the differentially expressed gene sets, giving 16 and 12 enriched GO terms in the up- and down-regulated gene sets, respectively (P < 0.05, Fisher's exact test, Table 1 and Fig 2B). The up-regulated genes contained terms involved in mycelial growth: mycelium development (GO:0043581), energy metabolism (GO:0006123 and GO:0015671), and biosynthesis of amino acids (GO:0006541, GO:0009082, GO:0009084, GO:0009450, and GO:0042026), in addition to lipid (GO:0016126 and GO:0072330), phosphate (GO:0070409), and NAD (GO:0034354). As summarized in Fig 1, ‘mycelium development,’ ‘sterol biosynthesis’, and ‘oxygen transport’ terms are closely related in the sterol biosynthesis process. We also examined the steroid biosynthesis pathway in the KEGG database (http://www.genome.jp/kegg-bin/show_pathway?mgr00100). Most genes in this pathway were highly induced under the hypoxic condition and identified as having the ‘sterol biosynthesis’ or ‘oxidation-reduction process’ terms (Fig 3). In the term ‘oxidation-reduction process’, oxygen-consuming enzymes like catalase (MGG_06442) and laccases (MGG_08523 and MGG_11608) were up-regulated, suggesting that lack of oxygen seems to activate oxygen-dependent processes to maintain normal levels of growth in the oxygen-limited environment. An increase in transcripts of catalase and laccase indicates that reactive oxygen species (ROS) might have accumulated in the cell under hypoxia. In addition, genes in the ‘copper ion transport’ term (MGG_02774, MGG_02283, MGG_00930, etc.) are involved in responses to ROS as well as copper homeostasis, supporting ROS accumulation.


Genome-Wide Analysis of Hypoxia-Responsive Genes in the Rice Blast Fungus, Magnaporthe oryzae.

Choi J, Chung H, Lee GW, Koh SK, Chae SK, Lee YH - PLoS ONE (2015)

The steroid biosynthesis pathway in M. oryzae.Intermediates are boxed in white and final products are boxed in black. Genes involved in the pathway are circled. Numbers in the gene names are gene IDs that start with ‘MGG.’ Up-regulated genes are colored in red and down-regulated genes in blue. ‘No significant regulation’ is colored in white.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4524601&req=5

pone.0134939.g003: The steroid biosynthesis pathway in M. oryzae.Intermediates are boxed in white and final products are boxed in black. Genes involved in the pathway are circled. Numbers in the gene names are gene IDs that start with ‘MGG.’ Up-regulated genes are colored in red and down-regulated genes in blue. ‘No significant regulation’ is colored in white.
Mentions: Gene Ontology (GO) enrichment analysis was conducted to understand functions of genes influenced by hypoxia. The R package ‘topGO’ was used to identify GO terms enriched in the differentially expressed gene sets, giving 16 and 12 enriched GO terms in the up- and down-regulated gene sets, respectively (P < 0.05, Fisher's exact test, Table 1 and Fig 2B). The up-regulated genes contained terms involved in mycelial growth: mycelium development (GO:0043581), energy metabolism (GO:0006123 and GO:0015671), and biosynthesis of amino acids (GO:0006541, GO:0009082, GO:0009084, GO:0009450, and GO:0042026), in addition to lipid (GO:0016126 and GO:0072330), phosphate (GO:0070409), and NAD (GO:0034354). As summarized in Fig 1, ‘mycelium development,’ ‘sterol biosynthesis’, and ‘oxygen transport’ terms are closely related in the sterol biosynthesis process. We also examined the steroid biosynthesis pathway in the KEGG database (http://www.genome.jp/kegg-bin/show_pathway?mgr00100). Most genes in this pathway were highly induced under the hypoxic condition and identified as having the ‘sterol biosynthesis’ or ‘oxidation-reduction process’ terms (Fig 3). In the term ‘oxidation-reduction process’, oxygen-consuming enzymes like catalase (MGG_06442) and laccases (MGG_08523 and MGG_11608) were up-regulated, suggesting that lack of oxygen seems to activate oxygen-dependent processes to maintain normal levels of growth in the oxygen-limited environment. An increase in transcripts of catalase and laccase indicates that reactive oxygen species (ROS) might have accumulated in the cell under hypoxia. In addition, genes in the ‘copper ion transport’ term (MGG_02774, MGG_02283, MGG_00930, etc.) are involved in responses to ROS as well as copper homeostasis, supporting ROS accumulation.

Bottom Line: However, such defects did not cause any significant decrease in disease severity.The other mutant, for the alcohol dehydrogenase gene MoADH1, showed no defect in the hypoxia-mimicking condition (using cobalt chloride) and fungal development.Taken together, this comprehensive transcriptional profiling in response to a hypoxic condition with experimental validations would provide new insights into fungal development and pathogenicity in plant pathogenic fungi.

View Article: PubMed Central - PubMed

Affiliation: Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 406-772, Korea.

ABSTRACT
Rice blast fungus, Magnaporthe oryzae, is the most destructive pathogen in the rice-growing area. This fungus has a biotrophic phase early in infection and later switches to a necrotrophic lifestyle. During the biotrophic phase, the fungus competes with its host for nutrients and oxygen. Continuous uptake of oxygen is essential for successful establishment of blast disease of this pathogen. Here, we report transcriptional responses of the fungus to oxygen limitation. Transcriptome analysis using RNA-Seq identified that 1,047 genes were up-regulated in response to hypoxia. Those genes are involved in mycelial development, sterol biosynthesis, and metal ion transport based on hierarchical GO terms, and are well-conserved among three fungal species. In addition, mutants of two hypoxia-responsive genes were generated and their roles in fungal development and pathogenicity tested. The mutant for the sterol regulatory element-binding protein gene, MoSRE1, exhibited increased sensitivity to a hypoxia-mimicking agent, increased conidiation, and delayed invasive growth within host cells, which is suggestive of important roles in fungal development. However, such defects did not cause any significant decrease in disease severity. The other mutant, for the alcohol dehydrogenase gene MoADH1, showed no defect in the hypoxia-mimicking condition (using cobalt chloride) and fungal development. Taken together, this comprehensive transcriptional profiling in response to a hypoxic condition with experimental validations would provide new insights into fungal development and pathogenicity in plant pathogenic fungi.

No MeSH data available.


Related in: MedlinePlus