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Updated: Jun 21, 2026
Structural Characterization of Mannan Cell Wall Polysaccharides in Plants Using PACE
Published on: October 16, 2017
Functional analysis of an alpha-1,2-mannosidase from Magnaporthe oryzae
Jie Zhou1, Cheng-zeng Lin, Xiang-zi Zheng
1The Ministry of Education Key Laboratory of Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, 350002, Fuzhou, China.
Abstract:
Identification of enzymes that are expressed during host colonization and characterization of their biochemical properties are prerequisite to understanding their role in the pathogen-host interaction. Nine alpha-1,2-mannosidase homologs were identified in the analysis of the Magnaporthe oryzae genome. Endoplasmic reticulum localized alpha-1,2-mannosidases play an important role in protein glycosylation. However, several members of the alpha-1,2-mannosidase gene family are predicted to be secreted. The biological role of such extracellular enzymes in host colonization has not been defined. Here, we characterized a secreted alpha-1,2-mannosidase of M. oryzae, MGG_00994.6, and found that the mature polypeptide is a glycoprotein capable of hydrolyzing alpha-1,2 linked mannobiose. The gene is expressed during growth in vitro and during colonization on rice plants, however, deletion of the gene did not affect pathogenicity. Five other members of the alpha-1,2-mannosidase of M. oryzae were expressed with a pattern similar to MGG_00994.6, suggesting the potential for functional redundancy. These results form the basis for additional studies on the role of this gene family in the rice blast fungus and its interaction with rice.
Insights
Researchers studied secreted alpha-1,2-mannosidase in Magnaporthe oryzae, a fungus that causes rice blast. Deleting the enzyme did not impact pathogenicity, suggesting other enzymes may compensate.
Area of Science:
- Plant Pathology
- Mycology
- Biochemistry
Background:
- Enzymes secreted by plant pathogens are crucial for host colonization.
- Alpha-1,2-mannosidases are involved in protein glycosylation, but their role in extracellular functions is unclear.
- Magnaporthe oryzae, the rice blast fungus, possesses multiple alpha-1,2-mannosidase genes.
Purpose of the Study:
- To characterize a specific secreted alpha-1,2-mannosidase (MGG_00994.6) from M. oryzae.
- To investigate the role of this enzyme in the interaction between M. oryzae and rice.
- To explore potential functional redundancy within the alpha-1,2-mannosidase gene family.
Main Methods:
- Bioinformatic analysis of the M. oryzae genome to identify alpha-1,2-mannosidase homologs.
- Biochemical characterization of the purified MGG_00994.6 enzyme.
- Gene deletion studies to assess pathogenicity.
- Expression analysis during in vitro growth and rice plant colonization.
Main Results:
- MGG_00994.6 is a secreted glycoprotein that hydrolyzes alpha-1,2 linked mannobiose.
- The gene MGG_00994.6 is expressed during fungal growth and rice colonization.
- Deletion of MGG_00994.6 did not significantly affect M. oryzae pathogenicity on rice.
- Other alpha-1,2-mannosidase genes showed similar expression patterns, indicating potential functional redundancy.
Conclusions:
- The characterized secreted alpha-1,2-mannosidase MGG_00994.6 does not appear essential for M. oryzae pathogenicity.
- Functional redundancy among alpha-1,2-mannosidase family members may explain the lack of a clear phenotype upon single gene deletion.
- Further research is needed to elucidate the precise roles of this gene family in rice-pathogen interactions.
