Fungus Derived Indole-3-Acetic Acid Controls Developmental Conidial Death in Magnaporthe oryzae

Area of Science:

• Plant Pathology
• Mycology
• Molecular Biology

Background:

• Ferroptotic cell death in Magnaporthe oryzae conidia is crucial for pathogenicity.
• The precise regulatory mechanisms of ferroptosis in fungal cells remain unclear.

Purpose of the Study:

• To elucidate the role of indole-3-acetic acid (IAA) in regulating ferroptotic conidial death and pathogenicity in Magnaporthe oryzae.
• To investigate the molecular mechanisms underlying IAA-mediated ferroptosis.

Main Methods:

• Characterization of IAA biosynthesis mutant (tam1Δ) and lipid metabolism gene mutant (ppoaΔ).
• Analysis of iron and lipid peroxide accumulation, conidial death, and pathogenicity.
• Investigation of the effects of exogenous phosphatidylethanolamines (PEs) on mutant phenotypes.
• Assessment of TAM1's role in autophagy via ATG8 gene transcription modulation.

Main Results:

• Elevated IAA levels promoted iron and lipid peroxide accumulation, increasing ferroptotic death.
• The tam1Δ mutant showed reduced conidial death correlated with lower endogenous IAA.
• The ppoaΔ mutant exhibited defects in conidial death, delayed appressorium formation, and reduced pathogenicity.
• Exogenous DOPE and SLPE partially restored defects in tam1Δ and ppoaΔ mutants.
• TAM1 was found to modulate ATG8 gene transcription, affecting autophagy.

Conclusions:

• Magnaporthe oryzae utilizes IAA to promote pathogenicity by inducing ferroptotic conidial death.
• IAA influences fungal pathogenicity through lipid metabolism and peroxidation pathways.
• Inhibitors of IAA synthesis present a promising theoretical basis for managing rice blast disease.