Transcriptome Analyses of Pre-parasitic and Parasitic Meloidogyne Chitwoodi Race 1 to Identify Putative Effector Genes

Lei Zhang,Cynthia Gleason

doi:10.21307/jofnem-2021-084

Lei Zhang, Cynthia Gleason

Open Access

https://doi.org/10.21307/jofnem-2021-084

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Abstract

Meloidogyne chitwoodi is a root-knot nematode that is a major pest of potato in the northwestern United States. Due to the lack of resistance against root-knot nematodes in potato, research has been undertaken to understand the M. chitwoodi-potato interaction at the molecular level. To identify the nematode genes that are playing roles in parasitism, we have performed transcriptome analyses on pre-parasitic and parasitic M. chitwoodi juveniles in susceptible potato. We compared gene expression profiles and identified genes that were significantly up- or down-regulated during nematode parasitism. Because parasitism proteins are typically secreted by the nematode to facilitate infection of host roots, we focused on the genes that encoded proteins that were predicted to be secreted. We found that approximately 34% (43/127) of the genes in the predicted secretome encoded proteins with no significant homology in the public genome databases, and 12% (15/127) encoded either a known effector, putative effectors or putative esophageal gland cell proteins. The transcriptome analyses of M. chitwoodi at the pre-parasitic and parasitic life stages shed light on the genes involved in nematode parasitism.

Highlights

Root-knot nematodes are microscopic, endoparasitic roundworms that are a major limiting factor in the production of potatoes, which are the fourth most important food crop in the world (Birch et al, 2012; Lima et al, 2018)
Meloidogyne chitwoodi (Golden et al, 1980) (Tylenchida: Meloidogynidae) is a root-knot nematode with limited worldwide distribution, and in the United States, M. chitwoodi is widely spread in the three states (Washington, Oregon, and Idaho) that produce over half of US potatoes (CABI/EPPO, 2012; Zasada et al, 2018)
Because of their critical roles in nematode parasitism, there has been a lot of interest in identifying root-knot nematode genes that are upregulated in expression during their parasitic life stages (Barcala et al, 2010; Caillaud et al, 2008; Dubreuil et al, 2007; Lee et al, 2019; Shukla et al, 2018)

Summary

Introduction

Root-knot nematodes are microscopic, endoparasitic roundworms that are a major limiting factor in the production of potatoes, which are the fourth most important food crop in the world (Birch et al, 2012; Lima et al, 2018). In order to reduce our reliance on nematicides and develop new forms of root-knot nematode resistance in potato, we must better our understanding of the plant-nematode interaction at the molecular level. Because of their critical roles in nematode parasitism, there has been a lot of interest in identifying root-knot nematode genes that are upregulated in expression during their parasitic life stages (Barcala et al, 2010; Caillaud et al, 2008; Dubreuil et al, 2007; Lee et al, 2019; Shukla et al, 2018). These criteria are indicative of nematode genes that encode secreted proteins; this study lays the groundwork for the future identification and characterization of M. chitwoodi secreted effectors

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