Related Experiment Videos
Identification and characterization of MPG1, a gene involved in pathogenicity from the rice blast fungus Magnaporthe
N J Talbot1, D J Ebbole, J E Hamer
1Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392.
Abstract:
Differential cDNA cloning was used to identify genes expressed during infectious growth of the fungal pathogen Magnaporthe grisea in its host, the rice plant. We characterized one of these genes, MPG1, in detail. Using a novel assay to determine the proportion of fungal biomass present in the plant, we determined that the MPG1 transcript was 60-fold more abundant during growth in the plant than in culture. Mpg1 mutants have a reduced ability to cause disease symptoms that appears to result from an impaired ability to undergo appressorium formation. MPG1 mRNA was highly abundant very early in plant infection concomitant with appressorium formation and was also abundant at the time of symptom development. The MPG1 mRNA was also expressed during conidiation and in mycelial cultures starved for nitrogen or carbon. MPG1 potentially encodes a small, secreted, cysteine-rich, moderately hydrophobic protein with the characteristics of a fungal hydrophobin. Consistent with the role of the MPG1 gene product as a hydrophobin, Mpg1 mutants show an "easily wettable" phenotype. Our results suggest that hydrophobins may have a role in the elaboration of infective structures by fungi and may fulfill other functions in fungal phytopathogenesis.
Insights
The fungal hydrophobin MPG1 is crucial for Magnaporthe grisea rice infection. MPG1 gene expression is vital for appressorium formation and disease development in this important plant pathogen.
Area of Science:
- Plant Pathology
- Mycology
- Molecular Biology
Background:
- Magnaporthe grisea is a significant fungal pathogen affecting rice crops.
- Understanding gene expression during fungal-plant interactions is key to developing control strategies.
Purpose of the Study:
- To identify and characterize genes involved in the infectious growth of Magnaporthe grisea in rice.
- To investigate the role of the MPG1 gene in fungal pathogenesis and development.
Main Methods:
- Differential cDNA cloning to identify expressed genes.
- A novel assay to quantify fungal biomass in planta.
- Construction and analysis of Mpg1 mutants.
Main Results:
- The MPG1 transcript was 60-fold more abundant during plant infection than in culture.
- Mpg1 mutants exhibited reduced pathogenicity due to impaired appressorium formation.
- MPG1 mRNA was highly expressed during early infection, symptom development, conidiation, and nutrient starvation.
Conclusions:
- MPG1 encodes a hydrophobin essential for Magnaporthe grisea infection structures and pathogenesis.
- Hydrophobins may play diverse roles in fungal phytopathogenesis, including the formation of infective structures.