A novel Meloidogyne enterolobii effector MeTCTP promotes parasitism by suppressing programmed cell death in host plants

Abstract

Meloidogyne enterolobii is one of the most important plant-parasitic nematodes that can overcome the Mi-1 resistance gene and damage many economically important crops. Translationally controlled tumour protein (TCTP) is a multifunctional protein that exists in various eukaryotes and plays an important role in parasitism. In this study, a novel M. enterolobii TCTP effector, named MeTCTP, was identified and functionally characterized. MeTCTP was specifically expressed within the dorsal gland and was up-regulated during M. enterolobii parasitism. Transient expression of MeTCTP in protoplasts from tomato roots showed that MeTCTP was localized in the cytoplasm of the host cells. Transgenic Arabidopsis thaliana plants overexpressing MeTCTP were more susceptible to M. enterolobii infection than wild-type plants in a dose-dependent manner. By contrast, in planta RNA interference (RNAi) targeting MeTCTP suppressed the expression of MeTCTP in infecting nematodes and attenuated their parasitism. Furthermore, MeTCTP could suppress programmed cell death triggered by the pro-apoptotic protein BAX. These results demonstrate that MeTCTP is a novel plant-parasitic nematode effector that promotes parasitism, probably by suppressing programmed cell death in host plants.

Research Article In silico modeling and characterization of phytoparasitic nematodes translationally-controlled tumor proteins.

“…This tool predicts the presence and location of signal peptide cleavage sites in protein sequences incorporating a prediction of cleavage sites and a signal peptide/non-signal peptide prediction based on a combination of several artificial neural networks. TOPCONS predicted that none of the evaluated sequences had an N-terminal signal peptide, this fact was expected as demonstrated by other studies that TCTP is secreted by a non-classical pathway without the aid of signal peptides (Amzallag et al, 2004, Bommer andThiele, 2004;Zhuo et al, 2016).…”

“…MeTCTP sequence described by Zhuo et al (2016) was used as query in the tool BLASTp from the National Center for Biotechnology Information (NCBI, http://www. ncbi.nlm.nih.gov) database.…”

“…It was first identified in mice (Yenofsky et al, 1982) and humans (Gross et al, 1989), and then in other organisms such as yeasts, invertebrates and plants (Bonnet et al, 2000;Gnanasekar et al, 2002;Rao et al, 2002;Hoepflinger et al, 2013). TCTP has been identified in the secretions of animal-parasitic nematodes , and of Meloidogyne enterolobii, a plant parasitic nematode (Zhuo et al, 2016). Expressed specifically within the dorsal oesophageal gland, which produces SEPs, M. enterolobii TCTP may play a role in suppressing the plant immunity and programmed cell, hence promoting nematode parasitism (Zhuo et al, 2016).…”

“…TCTP has been identified in the secretions of animal-parasitic nematodes , and of Meloidogyne enterolobii, a plant parasitic nematode (Zhuo et al, 2016). Expressed specifically within the dorsal oesophageal gland, which produces SEPs, M. enterolobii TCTP may play a role in suppressing the plant immunity and programmed cell, hence promoting nematode parasitism (Zhuo et al, 2016).…”

“…In addition to this, they secrete cell-wall degrading enzymes (CWDE) to allow migration through the plant root, and secretory effector proteins (SEP) to suppress host defense responses (Williamson and Gleason, 2003;Davis et al, 2004;Baum et al, 2007;Davis et al, 2008;Perry and Moens, 2011;Haegeman et al, 2012;Rai et al, 2015). In response to pathogen infection, plants can induce a hypersensitive reaction that causes a rapid death of cells surrounding the site of infection;thus, restricting the growth and spread of pathogens (Heath, 2000;Jones and Dangl, 2006;Chisholm et al, 2006;Zhuo et al, 2016). Ability to suppress this programmed cell death could be preponderant to successful parasitism in plant parasitic nematodes.…”