University of Dundee Identification and characterisation of a hyper-variable apoplastic effector gene family of the potato cyst nematodes

Sedentary endoparasitic nematodes are obligate biotrophs that modify host root tissues, using a suite of effector proteins to create and maintain a feeding site that is their sole source of nutrition. Using assumptions about the characteristics of genes involved in plant-nematode biotrophic interactions to inform the identification strategy, we provide a description and characterisation of a novel group of hyper-variable extracellular effectors termed HYP, from the potato cyst nematode Globodera pallida. HYP effectors comprise a large gene family, with a modular structure, and have unparalleled diversity between individuals of the same population: no two nematodes tested had the same genetic complement of HYP effectors. Individuals vary in the number, size, and type of effector subfamilies. HYP effectors are expressed throughout the biotrophic stages in large secretory cells associated with the amphids of parasitic stage nematodes as confirmed by in situ hybridisation. The encoded proteins are secreted into the host roots where they are detectable by immunochemistry in the apoplasm, between the anterior end of the nematode and the feeding site. We have identified HYP effectors in three genera of plant parasitic nematodes capable of infecting a broad range of monoand dicotyledon crop species. In planta RNAi targeted to all members of the effector family causes a reduction in successful parasitism. Citation: Eves-van den Akker S, Lilley CJ, Jones JT, Urwin PE (2014) Identification and Characterisation of a Hyper-Variable Apoplastic Effector Gene Family of the Potato Cyst Nematodes. PLoS Pathog 10(9): e1004391. doi:10.1371/journal.ppat. 1004391 Editor: David L. Williams, Rush University Medical Center, United States of America Received April 3, 2014; Accepted August 11, 2014; Published September 25, 2014 Copyright: 2014 Eves-van den Akker et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. HYP effectors present in the G. pallida genome assembly (GPLIN_001208400, GPLIN_001025300, GPLIN_001135100, GPLIN_000907700) available at: ftp://ftp.sanger. ac.uk/pub/pathogens/Globodera/pallida/ Gene_Predictions/ Unique genomic sequences for all amplified, cloned G. pallida HYP effectors are available at GenBank under accession numbers KM206198 to KM206272. Funding: SEvdA was supported by a Ph.D. studentship jointly funded by the UK Biotechnology and Biological Sciences Research Council (BBSRC) and The James Hutton Institute. The James Hutton Institute receives funding from the Scottish Government. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * Email: p.e. urwin@leeds.ac.uk