title: Quickly-released peroxidase of moss in defense against fungal invaders.
abstract: Mosses (Bryophyta) are nonvascular plants that constitute a large part of the photosynthesizing biomass and carbon storage on Earth. Little is known about how this important portion of flora maintains its health status. This study assessed whether the moss, Physcomitrella patens, responds to treatment with chitosan, a fungal cell wall-derived compound inducing defense against fungal pathogens in vascular plants. Application of chitosan to liquid culture of P. patens caused a rapid increase in peroxidase activity in the medium. For identification of the peroxidase(s), matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF)/MS, other methods and the whole-genome sequence of P. patens were utilized. Peroxidase gene knock-out mutants were made and inoculated with fungi. The peroxidase activity resulted from a single secreted class III peroxidase (Prx34) which belonged to a P. patens specific phylogenetic cluster in analysis of the 45 putative class III peroxidases of P. patens and those of Arabidopsis and rice. Saprophytic and pathogenic fungi isolated from another moss killed the Prx34 knockout mutants but did not damage wild-type P. patens. The data point out the first specific host factor that is pivotal for pathogen defense in a nonvascular plant. Furthermore, results provide conclusive evidence that class III peroxidases in plants are needed in defense against hostile invasion by fungi.
authors.affiliation: Department of Applied Biology, PO Box 27, FIN-00014 University of Helsinki, Finland.
authors.forename: Mikko T
authors.initials: MT
authors.lastname: Lehtonen
authors.affiliation: Department of Applied Biology, PO Box 27, FIN-00014 University of Helsinki, Finland.|Department of Biotechnological Sciences, Kinki University, Kinokawa, Wakayama, 649-6493, Japan.
authors.forename: Motomu
authors.initials: M
authors.lastname: Akita
authors.affiliation: Institute of Biotechnology, PO Box 65, FIN-00014 University of Helsinki, Finland.
authors.forename: Nisse
authors.initials: N
authors.lastname: Kalkkinen
authors.affiliation: Institute of Biotechnology, PO Box 65, FIN-00014 University of Helsinki, Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Ahola-Iivarinen
authors.affiliation: Institute of Biotechnology, PO Box 65, FIN-00014 University of Helsinki, Finland.
authors.forename: Gunilla
authors.initials: G
authors.lastname: Rönnholm
authors.affiliation: Department of Applied Biology, PO Box 27, FIN-00014 University of Helsinki, Finland.
authors.forename: Panu
authors.initials: P
authors.lastname: Somervuo
authors.affiliation: Department of Plant Biology and Forest Genetics, Box 7080, SLU, SE-750 07 Uppsala, Sweden.
authors.forename: Mattias
authors.initials: M
authors.lastname: Thelander
authors.affiliation: Department of Applied Biology, PO Box 27, FIN-00014 University of Helsinki, Finland.
authors.forename: Jari P T
authors.initials: JPT
authors.lastname: Valkonen
mesh_terms: D000595:Amino Acid Sequence; D019068:Bryopsida / Q000201:enzymology* / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D048271:Chitosan / Q000494:pharmacology; D017124:Conserved Sequence; D003470:Culture Media; D005091:Exons / Q000235:genetics; D005658:Fungi / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D055786:Gene Knockout Techniques; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010449:Peptide Mapping; D010544:Peroxidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D053719:Tandem Mass Spectrometry
chemical_list: D003470:Culture Media; D010940:Plant Proteins; D048271:Chitosan; D010544:Peroxidases