title: Functional C-TERMINALLY ENCODED PEPTIDE (CEP) plant hormone domains evolved de novo in the plant parasite Rotylenchulus reniformis.
abstract: Sedentary plant-parasitic nematodes (PPNs) induce and maintain an intimate relationship with their host, stimulating cells adjacent to root vascular tissue to re-differentiate into unique and metabolically active 'feeding sites'. The interaction between PPNs and their host is mediated by nematode effectors. We describe the discovery of a large and diverse family of effector genes, encoding C-TERMINALLY ENCODED PEPTIDE (CEP) plant hormone mimics (RrCEPs), in the syncytia-forming plant parasite Rotylenchulus reniformis. The particular attributes of RrCEPs distinguish them from all other CEPs, regardless of origin. Together with the distant phylogenetic relationship of R. reniformis to the only other CEP-encoding nematode genus identified to date (Meloidogyne), this suggests that CEPs probably evolved de novo in R. reniformis. We have characterized the first member of this large gene family (RrCEP1), demonstrating its significant up-regulation during the plant-nematode interaction and expression in the effector-producing pharyngeal gland cell. All internal CEP domains of multi-domain RrCEPs are followed by di-basic residues, suggesting a mechanism for cleavage. A synthetic peptide corresponding to RrCEP1 domain 1 is biologically active and capable of up-regulating plant nitrate transporter (AtNRT2.1) expression, whilst simultaneously reducing primary root elongation. When a non-CEP-containing, syncytia-forming PPN species (Heterodera schachtii) infects Arabidopsis in a CEP-rich environment, a smaller feeding site is produced. We hypothesize that CEPs of R. reniformis represent a two-fold adaptation to sustained biotrophy in this species: (i) increasing host nitrate uptake, whilst (ii) limiting the size of the syncytial feeding site produced.
authors.affiliation: Division of Plant Sciences, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.|Centre for Plant Sciences, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Eves-Van Den Akker
authors.affiliation: Centre for Plant Sciences, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Lilley
authors.affiliation: Centre for Plant Sciences, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Hazijah B
authors.initials: HB
authors.lastname: Yusup
authors.affiliation: Cell and Molecular Sciences Group, Dundee Effector Consortium, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.|School of Biology, University of St Andrews, North Haugh, St Andrews, KY16 9TZ, UK.
authors.forename: John T
authors.initials: JT
authors.lastname: Jones
authors.affiliation: Centre for Plant Sciences, University of Leeds, Leeds, LS2 9JT, UK. p.e.urwin@leeds.ac.uk.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Urwin
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D017360:Arabidopsis / Q000469:parasitology; D017238:Genes, Helminth; D006790:Host-Parasite Interactions; D005810:Multigene Family; D010271:Parasites / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D010614:Pharynx / Q000166:cytology; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000737:chemistry*; D000072417:Protein Domains; D016415:Sequence Alignment; D014431:Tylenchoidea / Q000235:genetics / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D010455:Peptides; D010937:Plant Growth Regulators
keywords: effector; evolution; plant peptide hormone; plant-parasitic nematode