Quickly‐released peroxidase of moss in defense against fungal invaders

Abstract

Summary• 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.

Arabidopsis peroxidase AtPRX53 influences cell elongation and susceptibility toHeterodera schachtii

“…[16][17][18] Genes coding for class III peroxidases have been duplicated extensively during evolution and thus form large gene families in all land plant species studied. 16 Some of these enzymes have been shown to be involved in a wide range of physiological and developmental processes, which include cross-linking of cell wall components during cell wall formation and modification, 19,20 Accumulated experimental evidence also implicates class III peroxidases in plant defense responses to pathogen/pest attacks, such as bacteria, [25][26][27] fungi, 28 viruses, 29 insects 30 and cyst nematodes. 31 Two major functional roles have been attributed to class III peroxidases in response to pathogen attack.…”

Involvement of a Class III Peroxidase and the Mitochondrial Protein TSPO in Oxidative Burst Upon Treatment of Moss Plants with a Fungal Elicitor

“…P. patens encodes a class III peroxidase (Prx34) that is released immediately to the extracellular space and culture medium upon treatment of the moss with a chitosan preparation (CHN) (Lehtonen et al 2009). The CHN preparation contains chitin, a fungal cell wall component that elicits pathogen defense in plants, and which is deacetylated to 90% in order to make it soluble in water (Knaul et al 1999;Shibuya and Minami 2001).…”

Proteomic analysis of secreted protein induced by a component of prey in pitcher fluid of the carnivorous plant Nepenthes alata

“…1, protein band 9). A similar case was reported by Lehtonen et al [19]. The addition of chitosan, which is derived from chitin by deacetylation, to a liquid-cultured moss (Physcomitrella patens) caused a rapid increase in peroxidase activity in the medium [19].…”