An array of signal-specific MoYpd1 isoforms determines full virulence in the pathogenic fungus Magnaporthe oryzae

TL;DR

The study shows how different versions of a protein in a plant pathogen help it become more harmful to its host.

Contribution

The discovery of signal-specific MoYpd1 isoforms and their role in orchestrating virulence in Magnaporthe oryzae is novel.

Findings

Three MoYpd1 isoforms are produced in a signal-specific manner in Magnaporthe oryzae.

Each isoform responds differently to external stress and contributes to virulence.

Mutant strains with only one isoform are less virulent, showing the need for isoform combinations.

Abstract

Magnaporthe oryzae is placed first on a list of the world’s top ten plant pathogens with the highest scientific and economic importance. The locus MGG_07173 occurs only once in the genome of M. oryzae and encodes the phosphotransfer protein MoYpd1p, which plays an important role in the high osmolarity glycerol (HOG) signaling pathway for osmoregulation. Originating from this locus, at least three MoYPD1 isoforms are produced in a signal-specific manner. The transcript levels of these MoYPD1-isoforms were individually affected by external stress. Salt (KCI) stress raised MoYPD1_T0 abundance, whereas osmotic stress by sorbitol elevates MoYPD1_T1 levels. In line with this, signal-specific nuclear translocation of green fluorescent protein-fused MoYpd1p isoforms in response to stress was observed. Mutant strains that produce only one of the MoYpd1p isoforms are less virulent, suggesting a combination thereof is required to invade the host successfully. In summary, we demonstrate signal-specific production of MoYpd1p isoforms that individually increase signal diversity and orchestrate virulence in M. oryzae.

This study suggests that signal-specific production of protein isoforms by alternative splicing individually increases diversity of signaling networks and orchestrates virulence in pathogenic fungi.

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