Abstract
The filamentous fungus Alternaria alternata includes seven pathogenic variants (pathotypes) which produce different host-selective toxins and cause diseases on different plants. The Japanese pear pathotype produces the host-selective AK-toxin, an epoxy-decatrienoic acid ester, and causes black spot of Japanese pear. Previously, we identified four genes, AKT1, AKT2, AKT3, and AKTR, involved in AK toxin biosynthesis. AKT1, AKT2, and AKT3 encode enzyme proteins with peroxisomal targeting signal type 1 (PTS1)-like tripeptides, SKI, SKL, and PKL, respectively, at the C-terminal ends. In this study, we verified the peroxisome localization of Akt1, Akt2, and Akt3 by using strains expressing N-terminal green fluorescent protein (GFP)-tagged versions of the proteins. To assess the role of peroxisome function in AK-toxin production, we isolated AaPEX6, which encodes a peroxin protein essential for peroxisome biogenesis, from the Japanese pear pathotype and made AaPEX6 disruption-containing transformants from a GFP-Akt1-expressing strain. The δAaPEX6 mutant strains did not grow on fatty acid media because of a defect in fatty acid oxidation. The import of GFP-Akt1 into peroxisomes was impaired in the δAaPEX6 mutant strains. These strains completely lost AK toxin production and pathogenicity on susceptible pear leaves. These data show that peroxisomes are essential for AK-toxin biosynthesis. The δAaPEX6 mutant strains showed a marked reduction in the ability to cause lesions on leaves of a resistant pear cultivar with defense responses compromised by heat shock. This result suggests that peroxisome function is also required for plant invasion and tissue colonization in A. alternata. We also observed that mutation of δAaPEX6 caused a marked reduction of conidiation.
| Original language | English |
|---|---|
| Pages (from-to) | 682-694 |
| Number of pages | 13 |
| Journal | Eukaryotic Cell |
| Volume | 9 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - May 2010 |
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ASJC Scopus subject areas
- Microbiology
- Molecular Biology
Cite this
Contribution of peroxisomes to secondary metabolism and pathogenicity in the fungal plant pathogen alternaria alternata. / Imazaki, Ai; Tanaka, Aiko; Harimoto, Yoshiaki; Yamamoto, Mikihiro; Akimitsu, Kazuya; Park, Pyoyun; Tsuge, Takashi.
In: Eukaryotic Cell, Vol. 9, No. 5, 05.2010, p. 682-694.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Contribution of peroxisomes to secondary metabolism and pathogenicity in the fungal plant pathogen alternaria alternata
AU - Imazaki, Ai
AU - Tanaka, Aiko
AU - Harimoto, Yoshiaki
AU - Yamamoto, Mikihiro
AU - Akimitsu, Kazuya
AU - Park, Pyoyun
AU - Tsuge, Takashi
PY - 2010/5
Y1 - 2010/5
N2 - The filamentous fungus Alternaria alternata includes seven pathogenic variants (pathotypes) which produce different host-selective toxins and cause diseases on different plants. The Japanese pear pathotype produces the host-selective AK-toxin, an epoxy-decatrienoic acid ester, and causes black spot of Japanese pear. Previously, we identified four genes, AKT1, AKT2, AKT3, and AKTR, involved in AK toxin biosynthesis. AKT1, AKT2, and AKT3 encode enzyme proteins with peroxisomal targeting signal type 1 (PTS1)-like tripeptides, SKI, SKL, and PKL, respectively, at the C-terminal ends. In this study, we verified the peroxisome localization of Akt1, Akt2, and Akt3 by using strains expressing N-terminal green fluorescent protein (GFP)-tagged versions of the proteins. To assess the role of peroxisome function in AK-toxin production, we isolated AaPEX6, which encodes a peroxin protein essential for peroxisome biogenesis, from the Japanese pear pathotype and made AaPEX6 disruption-containing transformants from a GFP-Akt1-expressing strain. The δAaPEX6 mutant strains did not grow on fatty acid media because of a defect in fatty acid oxidation. The import of GFP-Akt1 into peroxisomes was impaired in the δAaPEX6 mutant strains. These strains completely lost AK toxin production and pathogenicity on susceptible pear leaves. These data show that peroxisomes are essential for AK-toxin biosynthesis. The δAaPEX6 mutant strains showed a marked reduction in the ability to cause lesions on leaves of a resistant pear cultivar with defense responses compromised by heat shock. This result suggests that peroxisome function is also required for plant invasion and tissue colonization in A. alternata. We also observed that mutation of δAaPEX6 caused a marked reduction of conidiation.
AB - The filamentous fungus Alternaria alternata includes seven pathogenic variants (pathotypes) which produce different host-selective toxins and cause diseases on different plants. The Japanese pear pathotype produces the host-selective AK-toxin, an epoxy-decatrienoic acid ester, and causes black spot of Japanese pear. Previously, we identified four genes, AKT1, AKT2, AKT3, and AKTR, involved in AK toxin biosynthesis. AKT1, AKT2, and AKT3 encode enzyme proteins with peroxisomal targeting signal type 1 (PTS1)-like tripeptides, SKI, SKL, and PKL, respectively, at the C-terminal ends. In this study, we verified the peroxisome localization of Akt1, Akt2, and Akt3 by using strains expressing N-terminal green fluorescent protein (GFP)-tagged versions of the proteins. To assess the role of peroxisome function in AK-toxin production, we isolated AaPEX6, which encodes a peroxin protein essential for peroxisome biogenesis, from the Japanese pear pathotype and made AaPEX6 disruption-containing transformants from a GFP-Akt1-expressing strain. The δAaPEX6 mutant strains did not grow on fatty acid media because of a defect in fatty acid oxidation. The import of GFP-Akt1 into peroxisomes was impaired in the δAaPEX6 mutant strains. These strains completely lost AK toxin production and pathogenicity on susceptible pear leaves. These data show that peroxisomes are essential for AK-toxin biosynthesis. The δAaPEX6 mutant strains showed a marked reduction in the ability to cause lesions on leaves of a resistant pear cultivar with defense responses compromised by heat shock. This result suggests that peroxisome function is also required for plant invasion and tissue colonization in A. alternata. We also observed that mutation of δAaPEX6 caused a marked reduction of conidiation.
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UR - http://www.scopus.com/inward/citedby.url?scp=77953486651&partnerID=8YFLogxK
U2 - 10.1128/EC.00369-09
DO - 10.1128/EC.00369-09
M3 - Article
C2 - 20348386
AN - SCOPUS:77953486651
VL - 9
SP - 682
EP - 694
JO - Eukaryotic Cell
JF - Eukaryotic Cell
SN - 1535-9778
IS - 5
ER -