DNA transposon fossils present on the conditionally dispensable chromosome controlling AF-toxin biosynthesis and pathogenicity of Alternaria alternata

Hatta, Rieko; Shinjo, Akihisa; Ruswandi, S.; Kitani, K.; Yamamoto, Mikihiro; Akimitsu, Kazuya; Tsuge, Takashi

doi:10.1007/s10327-006-0277-9

Cited by 19 publications

(13 citation statements)

References 53 publications

(93 reference statements)

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“…Host‐selective toxin biosynthetic genes have been isolated from six pathotypes of A. alternata (Tsuge et al ., ).The gene clusters of A. alternata have unique features, such as the presence of multiple sets of clusters on a single chromosome, high‐density distribution of transposon‐like sequences in the clusters and storage of the clusters in single small chromosomes of <2.0 Mb in most strains tested (Tanaka et al ., ; Tanaka & Tsuge, ; Johnson et al ., ; Hatta et al ., , ; Masunaka et al ., ; Ruswandi et al ., ; Harimoto et al ., , ; Miyamoto et al ., , , ; Akagi et al ., ; Izumi et al ., ). Loss of the small chromosomes encoding toxin biosynthetic gene clusters was observed in the strawberry, apple and tomato pathotypes, and the small chromosomes appeared to be conditionally dispensable (CD) (Covert, ; Johnson et al ., ; Hatta et al ., ; Akagi et al ., ).…”

Section: Discussionmentioning

confidence: 97%

Complex regulation of secondary metabolism controlling pathogenicity in the phytopathogenic fungus Alternaria alternata

et al. 2014

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SummaryThe filamentous fungus Alternaria alternata includes seven pathogenic variants (pathotypes), which produce different host-selective toxins and cause disease on different plants. The Japanese pear, strawberry and tangerine pathotypes produce AK-toxin, AF-toxin and ACT-toxin, respectively, which have a common structural moiety, 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid (EDA).Here, we identified a new gene, AKT7 (AK-toxin biosynthetic gene 7), from the Japanese pear pathotype, which encodes a cytochrome P450 monooxygenase and functions to limit AK-toxin production.AKT7 homologs were found in the strawberry pathotype, but not the tangerine pathotype. However, the strawberry pathotype homolog appeared to include a premature stop codon. Although the Japanese pear pathotype strain has multiple copies of AKT7, a single-copy disruption resulted in mutants with increased production of AK-toxin and EDA. AKT7 overexpression in the three pathotypes caused marked reductions of toxin and EDA production, suggesting that Akt7 catalyzes a side reaction of EDA or its precursor. AKT7 overexpression caused reduced virulence in these pathotypes. We also found that AKT7 transcripts predominantly include misspliced mRNAs, which have premature stop codons.Our observations suggest that the AK-toxin production required for full virulence is regulated in a complex way by the copy number and intron information content of AKT7.

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Section: Discussionmentioning

confidence: 97%

Complex regulation of secondary metabolism controlling pathogenicity in the phytopathogenic fungus Alternaria alternata

et al. 2014

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“…Toxin biosynthetic genes appeared to be clustered on small chromosomes of \2.0 Mb in most strains of these pathotypes tested (Akamatsu et al 1999;Johnson et al 2001;Hatta et al 2002;Ito et al 2004;Akagi et al 2005;Masunaka et al 2005;Hatta et al 2006;Harimoto et al 2007). We identified that small chromosomes encoding toxin biosynthetic genes from the strawberry and tomato pathotypes are also CD chromosomes (Hatta et al 2002;Akagi et al 2005).…”

Section: Discussionmentioning

confidence: 75%

Multiple copies of AMT2 are prerequisite for the apple pathotype of Alternaria alternata to produce enough AM-toxin for expressing pathogenicity

et al. 2008

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The apple pathotype of Alternaria alternata produces the cyclic depsipeptide AM-toxin and causes Alternaria blotch of apple. Previously, we cloned AMT2 from the apple pathotype as an orthologue of AFTS1, which is required for biosynthesis of the decatrienoic acid ester AF-toxin I of the strawberry pathotype. These genes were predicted to encode aldo-keto reductases involved in biosynthesis of a common precursor, 2-hydroxy-isovaleric acid, of AF-toxin I and AM-toxin. In this study, we analyzed the function of AMT2 in AM-toxin biosynthesis in the apple pathotype. DNA gel blot analysis of the apple pathotype strain IFO8984 with five restriction enzymes suggested that this strain has a single copy of AMT2 in the genome. However, gene disruption experiments showed that IFO8984 probably has three copies of AMT2. We made mutants having one or two copies of AMT2 disrupted. The single-copy mutants produced less AM-toxin than did the wild type and were still as pathogenic as the wild type. The two-copy mutants produced trace or undetectable amounts of AM-toxin and were markedly reduced in pathogenicity. Thus, AMT2 was verified to be required for AM-toxin biosynthesis and hence pathogenicity. The fact that the two-copy mutants have a remaining copy of AMT2 suggests that multiple copies of AMT2 are prerequisite for the pathogen to produce enough AM-toxin for full pathogenicity.

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“…Strains from the Japanese pear and tangerine pathotypes showed the presence of the TLS-S2 copies, whereas it could not be detected in other pathotypes or in the nonpathogenic strain ( Fig. 2.5) (Hatta et al 2006). Some fungal pathogens have been reported to produce nonspecific phytotoxic compounds that have different actions on host plant tissues.…”

Section: Toxins Produced By Fungal Pathogensmentioning

confidence: 97%

“…Left: Pathotypes of strains: S-strawberry; Right: Jp, Japanese pear; Ta, tangerine; R, rough lemon; A, apple; Tm, tomato; Tb, tobacco; Np, nonpathogen. (Courtesy ofHatta et al 2006; The Phytopathological Society of Japan and Springer-Verlag, Tokyo)…”

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confidence: 99%

Molecular Biology in Plant Pathogenesis and Disease Management

2008

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DNA transposon fossils present on the conditionally dispensable chromosome controlling AF-toxin biosynthesis and pathogenicity of Alternaria alternata

Cited by 19 publications

References 53 publications

Complex regulation of secondary metabolism controlling pathogenicity in the phytopathogenic fungus Alternaria alternata

Complex regulation of secondary metabolism controlling pathogenicity in the phytopathogenic fungus Alternaria alternata

Multiple copies of AMT2 are prerequisite for the apple pathotype of Alternaria alternata to produce enough AM-toxin for expressing pathogenicity

Molecular Biology in Plant Pathogenesis and Disease Management

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