A Nucleolar Protein, MoRRP8 Is Required for Development and Pathogenicity in the Rice Blast Fungus

Area of Science:

• Cell Biology
• Mycology
• Molecular Biology

Background:

• The nucleolus is a key nuclear organelle involved in ribosome biogenesis and stress response.
• Nucleolar proteins mediate diverse nucleolar functions.
• The role of specific nucleolar proteins in fungal pathogenesis is not fully understood.

Purpose of the Study:

• To characterize the function of a putative nucleolar protein, MoRRP8, in the rice blast fungus, Magnaporthe oryzae.
• To investigate the role of MoRRP8 in fungal development, sporulation, and pathogenicity.

Main Methods:

• Phylogenetic and domain analysis of the MoRRP8 gene.
• Gene deletion and creation of a ΔMorrp8 mutant.
• Confocal microscopy using fluorescent protein fusions (GFP and RFP) to confirm nucleolar localization.
• Assessment of vegetative growth, asexual sporulation, spore germination, appressorium formation, and pathogenicity.

Main Results:

• MoRRP8 was identified as a nucleolar protein in Magnaporthe oryzae, orthologous to Rrp8 in yeast.
• Deletion of MoRRP8 resulted in reduced vegetative growth and impaired asexual sporulation.
• ΔMorrp8 mutants exhibited delayed spore germination and reduced appressorium formation.
• MoRRP8 is crucial for the full virulence and in-planta growth of Magnaporthe oryzae.

Conclusions:

• MoRRP8 is a vital nucleolar protein in Magnaporthe oryzae.
• Nucleolar function mediated by MoRRP8 is critical for fungal development and pathogenesis.
• Targeting MoRRP8 could be a strategy for controlling rice blast disease.