PTS1 Peroxisomal Import Pathway Plays Shared and Distinct Roles to PTS2 Pathway in Development and Pathogenicity of Magnaporthe oryzae

Abstract

Peroxisomes participate in various important metabolisms and are required in pathogenicity of fungal plant pathogens. Peroxisomal matrix proteins are imported from cytoplasm into peroxisomes through peroxisomal targeting signal 1 (PTS1) or peroxisomal targeting signal 2 (PTS2) import pathway. PEX5 and PEX7 genes participate in the two pathways respectively. The involvement of PEX7 mediated PTS2 import pathway in fungal pathogenicity has been documented, while that of PTS1 remains unclear. Through null mutant analysis of MoPEX5, the PEX5 homolog in Magnaporthe oryzae, we report the crucial roles of PTS1 pathway in the development and host infection in the rice blast fungus, and compared with those of PTS2. We found that MoPEX5 disruption specifically blocked the PTS1 pathway. Δmopex5 was unable to use lipids as sole carbon source and lost pathogenicity completely. Similar as Δmopex7, Δmopex5 exhibited significant reduction in lipid utilization and mobilization, appressorial turgor genesis and H2O2 resistance. Additionally, Δmopex5 presented some distinct defects which were undetected in Δmopex7 in vegetative growth, conidial morphogenesis, appressorial morphogenesis and melanization. The results indicated that the PTS1 peroxisomal import pathway, in addition to PTS2, is required for fungal development and pathogenicity of the rice blast fungus, and also, as a main peroxisomal import pathway, played a more predominant role than PTS2.

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].…”

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

“…Nile red staining and fluorescein diacetate (FDA) staining were performed as previously described [33], and the fluorescence was observed under an Olympus Xa21 fluorescent microscope with filters adapted to excitation 495 nm and emission 520 nm. (Tokyo, Japan).…”

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

“…In M. oryzae , MoPEX5 and MoPEX6 had been identified to participate in PTS1 matrix protein import2629. 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 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.…”

“…Moreover, several genes associated with peroxisome metabolism, such as PTH2, MFP1, and MLS1, have also been identified and analyzed25262728. 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.…”