MoPex19, which Is Essential for Maintenance of Peroxisomal Structure and Woronin Bodies, Is Required for Metabolism and Development in the Rice Blast Fungus

Abstract

Peroxisomes are present ubiquitously and make important contributions to cellular metabolism in eukaryotes. They play crucial roles in pathogenicity of plant fungal pathogens. The peroxisomal matrix proteins and peroxisomal membrane proteins (PMPs) are synthesized in the cytosol and imported post-translationally. Although the peroxisomal import machineries are generally conserved, some species-specific features were found in different types of organisms. In phytopathogenic fungi, the pathways of the matrix proteins have been elucidated, while the import machinery of PMPs remains obscure. Here, we report that MoPEX19, an ortholog of ScPEX19, was required for PMPs import and peroxisomal maintenance, and played crucial roles in metabolism and pathogenicity of the rice blast fungus Magnaporthe oryzae. MoPEX19 was expressed in a low level and Mopex19p was distributed in the cytoplasm and newly formed peroxisomes. MoPEX19 deletion led to mislocalization of peroxisomal membrane proteins (PMPs), as well peroxisomal matrix proteins. Peroxisomal structures were totally absent in Δmopex19 mutants and woronin bodies also vanished. Δmopex19 exhibited metabolic deficiency typical in peroxisomal disorders and also abnormality in glyoxylate cycle which was undetected in the known mopex mutants. The Δmopex19 mutants performed multiple disorders in fungal development and pathogenicity-related morphogenesis, and lost completely the pathogenicity on its hosts. These data demonstrate that MoPEX19 plays crucial roles in maintenance of peroxisomal and peroxisome-derived structures and makes more contributions to fungal development and pathogenicity than the known MoPEX genes in the rice blast fungus.

Crosstalk between SNF1 Pathway and the Peroxisome-Mediated Lipid Metabolism in Magnaporthe oryzae

“…In M. oryzae , mutants with abnormal peroxisomes such as ΔMopex6 [30], ΔMopex5 [34], ΔMopex7 [33], and ΔMopex19 [41] showed inability to metabolize fatty acids and NaAC. In addition, yeast Δsnf1 and Δsnf4 were reported to be devoid of peroxisomal structures [38].…”

Identification and characterization of the peroxin 1 gene MoPEX1 required for infection-related morphogenesis and pathogenicity in Magnaporthe oryzae

“…MoPEX7 contributes to the import of PTS2 matrix proteins30. Recently, it has been reported that the imports of PTS1- and PTS2-containing matrix proteins were impaired in the ΔMopex19 mutants31. In this study, we compared the distribution of GFP-PTS1 and PTS2-GFP in the wild-type strain and ΔMopex1 mutants.…”

“…Moreover, we also transformed GFP-PMP47, a fusion representing the integral peroxisomal membrane proteins31, into the wild-type strain and ΔMopex1 mutants. Although the florescence was generally in punctate pattern, diffuse florescence could be detected in the conidia of the ΔMopex1 /GFP-PMP47, in contrast to the absolute punctate pattern in the wild type.…”

“…In C. lagenarium , the deficiency of peroxisomal function in the ΔClpex6 mutants leads to its inability to utilize long-chain fatty acids2425. In M. oryzae, the peroxisome-related mutants, ΔMopex5, ΔMopex6, and ΔMopex7, were unable to utilize long-chain fatty acids as sole carbon sources and ΔMopex19 mutants showed severe growth reduction when cultured with long-chain fatty acids26293031. Moreover, yeast cells deficient in Pex1 also show a characteristic phenotype with the inability to grow on oleic acid as sole carbon source4344.…”

“…Recently, in M. oryzae , it has been demonstrated that MoPEX5 and MoPEX7 are both required for host infection, although MoPEX5 plays a predominant role2930. In addition, deletion of MoPEX19 led to metabolic deficiency involved in peroxisomes, and consequently, failure to penetrate the host31.…”