The Pex3-mediated peroxisome biogenesis plays a critical role in metabolic biosynthesis, stress response, and pathogenicity in Alternaria alternata.

Peroxisomes are microbodies involved in the metabolism of fatty acids and hydrogen peroxide (HO) in eukaryotes. In the current study, an AaPex3 gene encoding a peroxisome membrane protein was demonstrated to be required for peroxisome biogenesis and resistance to peroxides and superoxide-generating compounds. Deleting AaPex3 affected the expression of the genes encoding the NADPH oxidase (NoxA) and the Yap1 stress-responsive transcription regulator, both of which have been implicated in ROS resistance.

Pexophagy is critical for fungal development, stress response, and virulence in Alternaria alternata.

Alternaria alternata can resist high levels of reactive oxygen species (ROS). The protective roles of autophagy or autophagy-mediated degradation of peroxisomes (termed pexophagy) against oxidative stress remain unclear. The present study, using transmission electron microscopy and fluorescence microscopy coupled with a GFP-AaAtg8 proteolysis assay and an mCherry tagging assay with peroxisomal targeting tripeptides, demonstrated that hydrogen peroxide (H O ) and nitrogen depletion induced autophagy and pexophagy.

Proper Functions of Peroxisomes Are Vital for Pathogenesis of Citrus Brown Spot Disease Caused by .

In addition to the production of a host-selective toxin, the tangerine pathotype of must conquer toxic reactive oxygen species (ROS) in order to colonize host plants. The roles of a peroxin 6-coding gene () implicated in protein import into peroxisomes was functionally characterized to gain a better understanding of molecular mechanisms in ROS resistance and fungal pathogenicity. The peroxisome is a vital organelle involved in metabolisms of fatty acids and hydrogen peroxide in eukaryotes.

Biotin biosynthesis affected by the NADPH oxidase and lipid metabolism is required for growth, sporulation and infectivity in the citrus fungal pathogen Alternaria alternata.

The tangerine pathotype of Alternaria alternata affects many citrus cultivars, resulting in yield losses. The capability to produce the host-selective toxin and cell-wall-degrading enzymes and to mitigate toxic reactive oxygen species is crucial for A. alternata pathogenesis to citrus.