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MAGNAPORTHE ORYZAE
Why in news?
Recently, Scientists have warned that the fungus Magnaporthe oryzae, which is destroying South American wheat crops, could spread worldwide. The pathogen affects the crop in a disease known as ‘wheat blast’.
More on news:
- The filamentous fungus Magnaporthe oryzae causes rice blast, the most serious disease of cultivated rice. Cellular differentiation of M. oryzae forms an infection structure called the appressorium, which generates enormous cellular turgor that is sufficient to rupture the plant cuticle.
- Rice blast is caused by the ascomycete fungus Magnaporthe oryzae and is the most serious disease of cultivated rice.
- The fungus is genetically tractable, has a sequenced genome and is experimentally amenable to study using functional genomics and cell biology.
- The fungus elaborates specialized cells called appressoria to infect plants.
- Appressorium development is cell cycle regulated and involves autophagic programmed cell death of the fungal spore. The cyclic AMP response pathway and the Pmk1 mitogen-activated protein kinase kinase pathway are necessary for appressorium development.
- Appressorium turgor generation involves accumulation of compatible solutes, including glycerol, which are derived from storage products in spores. Glycerol accumulation and melanization of the cell wall allow the deployment of sufficient turgor to breach the plant cuticle.
- The fungus spreads biotrophically in epidermal cells and might use protein effectors and/or secondary metabolites to suppress host defences.
- Disease symptoms involve necrosis of plant cells, which produces characteristic spreading lesions from which the fungus sporulates.
- Disease control by deployment of resistance genes, biotechnological approaches and development of new fungicides is an important aim of research on rice blast.