title: Cloning and characterization of a cyclic peptide synthetase gene from Alternaria alternata apple pathotype whose product is involved in AM-toxin synthesis and pathogenicity.
abstract: Afternaria afternata apple pathotype causes Alternaria blotch of susceptible apple cultivars through the production of a cyclic peptide host-specific toxin, AM-toxin. PCR (polymerase chain reaction), with primers designed to conserved domains of peptide synthetase genes, amplified several products from A. alternata apple pathotype that showed high similarity to other fungal peptide synthetases and were specific to the apple pathotype. Screening of a Lambda Zap genomic library with these PCR-generated probes identified overlapping clones containing a complete cyclic peptide synthetase gene of 13.1 kb in length with no introns. Disruption of this gene, designated AM-toxin synthetase (AMT), by transformation of wild-type A. afternata apple pathotype with disruption vectors resulted in toxin-minus mutants, which were also unable to cause disease symptoms on susceptible apple cultivars. AM-toxin synthetase is therefore a primary determinant of virulence and specificity in the A. alternata apple pathotype/apple interaction.
authors.affiliation: Laboratory of Plant Pathology, Faculty of Agriculture, Tottori University, Japan. rjohns19@wvu.edu
authors.forename: R D
authors.initials: RD
authors.lastname: Johnson
authors.forename: L
authors.initials: L
authors.lastname: Johnson
authors.forename: Y
authors.initials: Y
authors.lastname: Itoh
authors.forename: M
authors.initials: M
authors.lastname: Kodama
authors.forename: H
authors.initials: H
authors.lastname: Otani
authors.forename: K
authors.initials: K
authors.lastname: Kohmoto
mesh_terms: D000528:Alternaria / Q000201:enzymology* / Q000235:genetics* / Q000472:pathogenicity; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D005638:Fruit / Q000382:microbiology*; D008969:Molecular Sequence Data; D009183:Mycotoxins / Q000096:biosynthesis; D010453:Peptide Synthases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010456:Peptides, Cyclic / Q000096:biosynthesis*; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014774:Virulence / Q000235:genetics; D047630:Depsipeptides
chemical_list: D009183:Mycotoxins; D010453:Peptide Synthases; D010456:Peptides, Cyclic; C028572:AM toxin I; D047630:Depsipeptides; C021614:AM toxin II; C034125:AM toxin III; C414537:AM-toxin synthetase