Pan2-Pan3 Complex-Mediated Deadenylation Enforces mRNA Quality Control for Infection of the Rice Blast Fungus

Area of Science:

• Molecular Biology
• Mycology
• Post-transcriptional Regulation

Background:

• Poly(A) tail shortening by deadenylases is crucial for mRNA fate and eukaryotic development.
• The role of deadenylation in fungal pathogenesis, particularly in plant-pathogenic fungi, is largely unknown.

Purpose of the Study:

• To investigate the function of the Pan2-Pan3 deadenylase complex in the virulence of the rice blast fungus, Magnaporthe oryzae.
• To elucidate the molecular mechanisms by which Pan2-Pan3 impacts fungal infection processes.

Main Methods:

• Genetic deletion of Pan2 and/or Pan3 genes in Magnaporthe oryzae.
• Localization studies of the Pan2-Pan3 complex to P-bodies.
• Poly(A) tail length analysis (poly(A)-seq) and transcriptome profiling (RNA-seq).
• Phenotypic analysis of mutant strains, including appressorium maturation, nutrient mobilization, and autophagy.

Main Results:

• The Pan2-Pan3 complex is essential for virulence in Magnaporthe oryzae, with mutants showing severe defects in infection.
• Deletion of Pan2 or Pan3 disrupts mRNA quality control by abolishing poly(A) tail trimming.
• Mutants exhibit arrested appressorium maturation, impaired nutrient mobilization, and defective autophagy.
• Poly(A)-seq and RNA-seq identified 390 mRNAs with longer poly(A) tails and elevated levels in the Δpan2Δpan3 mutant.
• Key virulence genes like ATG5, GLS2, and DES1 are directly deadenylated by Pan2-Pan3, and their destabilization impairs infection.

Conclusions:

• The Pan2-Pan3 deadenylase complex is a master regulator of fungal virulence in Magnaporthe oryzae.
• This complex enforces mRNA quality control through poly(A) tail shortening, impacting essential infection processes.
• Pan2-Pan3-mediated deadenylation represents a critical post-transcriptional regulatory layer controlling fungal pathogenesis and offers a potential target for crop protection strategies.