title: Chitosan enhances parasitism of Meloidogyne javanica eggs by the nematophagous fungus Pochonia chlamydosporia.
abstract: Pochonia chlamydosporia (Pc), a nematophagous fungus and root endophyte, uses appressoria and extracellular enzymes, principally proteases, to infect the eggs of plant parasitic nematodes (PPN). Unlike other fungi, Pc is resistant to chitosan, a deacetylated form of chitin, used in agriculture as a biopesticide to control plant pathogens. In the present work, we show that chitosan increases Meloidogyne javanica egg parasitism by P. chlamydosporia. Using antibodies specific to the Pc enzymes VCP1 (a subtilisin), and SCP1 (a serine carboxypeptidase), we demonstrate chitosan elicitation of the fungal proteases during the parasitic process. Chitosan increases VCP1 immuno-labelling in the cell wall of Pc conidia, hyphal tips of germinating spores, and in appressoria on infected M. javanica eggs. These results support the role of proteases in egg parasitism by the fungus and their activation by chitosan. Phylogenetic analysis of the Pc genome reveals a large diversity of subtilisins (S8) and serine carboxypeptidases (S10). The VCP1 group in the S8 tree shows evidence of gene duplication indicating recent adaptations to nutrient sources. Our results demonstrate that chitosan enhances Pc infectivity of nematode eggs through increased proteolytic activities and appressoria formation and might be used to improve the efficacy of M. javanica biocontrol.
authors.affiliation: Laboratory of Plant Pathology, Department of Marine Sciences and Applied Biology, Multidisciplinary Institute for Environmental Studies (MIES) Ramon Margalef, University of Alicante, E-03080, Alicante, Spain. Electronic address: nuria.escudero@ua.es.
authors.forename: Nuria
authors.initials: N
authors.lastname: Escudero
authors.affiliation: Laboratory of Immunology and Genomic of Parasites, Department of Parasitology, Institute of Biological Science, Federal University of Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Sebastião R
authors.initials: SR
authors.lastname: Ferreira
authors.affiliation: Laboratory of Plant Pathology, Department of Marine Sciences and Applied Biology, Multidisciplinary Institute for Environmental Studies (MIES) Ramon Margalef, University of Alicante, E-03080, Alicante, Spain.
authors.forename: Federico
authors.initials: F
authors.lastname: Lopez-Moya
authors.affiliation: Centre for Genomic Regulation Comparative Genomics Group, Barcelona, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Naranjo-Ortiz
authors.affiliation: Laboratory of Plant Pathology, Department of Marine Sciences and Applied Biology, Multidisciplinary Institute for Environmental Studies (MIES) Ramon Margalef, University of Alicante, E-03080, Alicante, Spain.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Marin-Ortiz
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Thornton
authors.affiliation: Laboratory of Plant Pathology, Department of Marine Sciences and Applied Biology, Multidisciplinary Institute for Environmental Studies (MIES) Ramon Margalef, University of Alicante, E-03080, Alicante, Spain.
authors.forename: Luis V
authors.initials: LV
authors.lastname: Lopez-Llorca
mesh_terms: D000818:Animals; D048271:Chitosan / Q000378:metabolism*; D006790:Host-Parasite Interactions; D006999:Hypocreales / Q000187:drug effects* / Q000254:growth & development*; D014431:Tylenchoidea / Q000382:microbiology*; D015053:Zygote / Q000382:microbiology*
chemical_list: D048271:Chitosan
keywords: Appressorium development; Biocontrol; Egg-parasitism; Immunolocalization; Serine carboxypeptidases; Serine proteases