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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Publications at this Location » Publication #256187

Title: Generation of reactive oxygen species via NOXa is important for development and pathogenicity of mycosphaerella graminicola

Author
item Choi, Yoon-e
item Goodwin, Stephen - Steve
item Lee, Changsu - Chonbuk National University

Submitted to: Mycobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2016
Publication Date: 3/31/2016
Citation: Choi, Y., Goodwin, S.B., Lee, C. 2016. Generation of reactive oxygen species via NOXa is important for development and pathogenicity of mycosphaerella graminicola. Mycobiology. 44(1):38-47.

Interpretive Summary: The fungus Mycosphaerella graminicola is an important pathogen of wheat causing economically significant losses worldwide. The primary nutritional mode of this fungus is thought to be hemibiotrophic. This pathogenic lifestyle is associated with an early biotrophic stage of nutrient uptake from living cells followed by a necrotrophic stage after killing the cells, aided possibly by production of a toxin. In many other fungi, the genes CREA and AREA are important during the biotrophic stage of infection, while the NOXa gene product is important during necrotrophic growth. To test the hypothesis that these genes are important for pathogenicity of M. graminicola, we employed a strategy to increase the expression of the selected target genes CREA, AREA, and NOXa, because they might function as regulators of nutrient acquisition or toxin production. Increased expressions of these genes in M. graminicola were confirmed via molecular methods and strains were subsequently assayed for pathogenicity. Among them, over expression of NOXa but not the other genes resulted in significantly increased virulence. Moreover, instead of the usual growth form, we observed a predominance of yeast-like growth of this over-expression strain, which was correlated with toxin production. Our data indicate that toxin generation via the NOXa gene is important to pathogenicity as well as development in M. graminicola. This information will be useful to fungal geneticists and evolutionary biologists to better understand the genetics and evolution of M. graminicola. Plant pathologists may be able to use this information to design improved strategies for disease management, particularly once the biochemical basis for the observed changes is better understood.

Technical Abstract: The ascomycete fungus Mycosphaerella graminicola is an important pathogen of wheat causing economically significant losses. The primary nutritional mode of this fungus is thought to be hemibiotrophic. This pathogenic lifestyle is associated with an early biotrophic stage of nutrient uptake followed by a necrotrophic stage aided possibly by production of a toxin or reactive oxygen species (ROS). In many other fungi, the genes CREA and AREA are important during the biotrophic stage of infection, while the NOXa gene product is important during necrotrophic growth. To test the hypothesis that these genes are important for pathogenicity of M. graminicola, we employed an over-expression strategy for the selected target genes CREA, AREA, and NOXa, which might function as regulators of nutrient acquisition or ROS generation. Increased expressions of CREA, AREA, and NOXa in M. graminicola were confirmed via q-RT PCR and strains were subsequently assayed for pathogenicity. Among them, the NOXa over-expression strain, NO2, resulted in significantly increased virulence. Moreover, instead of the usual filamentous growth, we observed a predominance of yeast-like growth of NO2 which was correlated with ROS production. Our data indicate that ROS generation via NOXa is important to pathogenicity as well as development in M. graminicola.