Nematode Parasitism Genes

Abstract

The ability of nematodes to live on plant hosts involves multiple parasitism genes. The most pronounced morphological adaptations of nematodes for plant parasitism include a hollow, protrusible stylet (feeding spear) connected to three enlarged esophageal gland cells that express products that are secreted into plant tissues through the stylet. Reverse genetic and expressed sequence tag (EST) approaches are being used to discover the parasitism genes expressed in nematode esophageal gland cells. Some genes cloned from root-knot (Meloidogyne spp.) and cyst (Heterodera and Globodera spp.) nematodes have homologues reported in genomic analyses of Caenorhabditis elegans and animal-parasitic nematodes. To date, however, the candidate parasitism genes endogenous to the esophageal glands of plant nematodes (such as the ß-1,4-endoglucanases) have their greatest similarity to microbial genes, prompting speculation that genes for plant parasitism by nematodes may have been acquired by horizontal gene transfer.

Rooteomics: The Challenge of Discovering Plant Defense-Related Proteins in Roots

“…One avenue left to explore remains the possibility of studying the pathogen and the root individual proteomes upon interaction. The specific structures formed within the root tissue upon infection, such as specialized giant cells in the case of nematode infection [35], or localized infected cell populations could well be the target of specific proteomic studies. To this end, the application of laser capture microdissection could prove a powerful new tool towards the isolation of these structures and advance the understanding of the proteomic profiles of the initial stages of root infection.…”

Secrets in secretions: genes that control nematode parasitism of plants

“…These stylet secretions have a direct role in infection and parasitism of plants, and developmental changes in the secreted proteins occur during the parasitic cycle (Hussey, 1989;Davis et al, 2000). Herein, the secreted products of the parasitism genes expressed in the nematode's esophageal gland cells are considered collectively as the "parasitome", a subset of the secretome (secreted proteins) of a parasite that mediates parasitism (based upon the nomenclature in Greenbaum et al, 2001).…”

“…Secretory gland cells in the nematode esophagus are the principal sources of secretions involved in plant parasitism, and these gland cells enlarged considerably as nematodes evolved from microbial-feeding nematodes to become parasites of higher plants. Likewise the function of the secretions produced by the esophageal gland cells also evolved to enable nematodes to feed on plant cells and modify them into complex feeding cells (Hussey, 1989;Davis et al, 2000). Recent discoveries also suggest that some genes encoding esophageal gland secretions of plant-parasitic nematodes may have been acquired via horizontal gene transfer from prokaryotic microbes Davis et al, 2000).…”

SNPs of CLAVATA receptors in tomato, in the context of root-knot nematode infection

“…To gain insight into the establishment of nematode parasitic interactions with host plants, many efforts to identify "parasitic genes" have been carried out with different nematode species (Davis et al, 2000;Davis et al, 2008). In general, parasitic effector proteins produced in the esophageal gland cells of nematodes are secreted from the nematode through its stylet into the plant tissue (Davis et al, 2000;Davis et al, 2008).…”

“…In general, parasitic effector proteins produced in the esophageal gland cells of nematodes are secreted from the nematode through its stylet into the plant tissue (Davis et al, 2000;Davis et al, 2008). Attempts to target secretory proteins from the esophageal gland cells of the soybean cyst nematode Heterodera glycines at the parasitic stage identified HgCLE1 (formerly known as 2B10 and identical to Hg-SYV46) and HgCLE2 (known as 4G12), which encode a protein that harbors the C-terminal CLE domain (Wang et al, 2001;Gao et al, 2003;Wang et al, 2010).…”