A root‐knot nematode‐secreted protein is injected into giant cells and targeted to the nuclei

Abstract

Summary• Root-knot nematodes (RKNs) are obligate endoparasites that maintain a biotrophic relationship with their hosts over a period of several weeks and induce the differentiation of root cells into specialized feeding cells. Nematode effectors synthesized in the oesophageal glands and injected into the plant tissue through the syringe-like stylet certainly play a central role in these processes.• In a search for nematode effectors, we used comparative genomics on expressed sequence tag (EST) datasets to identify Meloidogyne incognita genes encoding proteins potentially secreted upon the early steps of infection.• We identified three genes specifically expressed in the oesophageal glands of parasitic juveniles that encode predicted secreted proteins. One of these genes, Mi-EFF1 is a pioneer gene that has no similarity in databases and a predicted nuclear localization signal. We demonstrate that RKNs secrete Mi-EFF1 within the feeding site and show Mi-EFF1 targeting to the nuclei of the feeding cells.• RKNs were previously shown to secrete proteins in the apoplasm of infected tissues. Our results show that nematodes sedentarily established at the feeding site also deliver proteins within plant cells through their stylet. The protein Mi-EFF1 injected within the feeding cells is targeted at the nuclei where it may manipulate nuclear functions of the host cell.

Structural characterization and localization analysis of the root-knot nematode Meloidogyne javanica fatty acid and retinol binding protein (Mj-FAR-1)

“…Targeting of the nematode-secreted proteins to the nucleus is biologically relevant and several studies have suggested that plant-parasitic nematodes manipulate functions of the plant cell nucleus during the interaction (Elling et al 2007;Jaouannet et al 2012;Jaouannet and Rosso 2013). Similarly, a growing number of effectors isolated from viruses, bacteria, phytoplasmas, oomycetes and fungi have been shown to be targeted to the nucleus of the plant cell where they manipulate plant functions to promote infection (Deslandes and Rivas 2011).…”

Effect of chemical stress imposed by Solanum nigrum in calreticulin and beta-1,4- endoglucanase genes and in infectivity of Pratylenchus goodeyi

“…It is known that these processes are facilitated by effector genes, such as calreticulin (crt) and beta-1,4-endoglucanase (eng), which products are secreted by parasites to facilitate penetration, migration and to counter plant defence responses (Rosso et al 1999;Abad et al 2003;Jaubert et al 2005;Jaouannet et al 2012).…”

Role of phytohormones (indol acetic acid, jasmonic acid, salcylic acid, and ethylene) in nematode-plant interactions

“…Sedentary endoparasitic nematodes are obligate biotrophs that can establish successful relationships with their host plants by inducing redifferentiation of root cells into specific feeding cells (Jaouannet et al, 2012). The development of nematodes is determined by their success in establishing feeding cells.…”