Secrets in secretions: genes that control nematode parasitism of plants

Abstract

The most evolutionary advanced adaptations for plant parasitism by nematodes are the products of parasitism genes expressed in their esophageal gland cells and secreted through their stylet into host tissue to control the complex process of parasitism. Molecular analyses of nematode parasitism genes are revealing the complexity of the tools that enable the nematode to attack plants, and the results paint a more elaborate picture of host cellular events under specific control by the parasite than previously hypothesized. Interestingly, the majority of the parasitism genes discovered encodes proteins unique to plant-parasitic nematodes. Identifying the nematode parasitome, i.e., the complete profile of parasitism gene products secreted through the nematode stylet during the parasitic cycle, is the key to understanding the molecular basis of nematode parasitism of plants. Such knowledge will identify vulnerable points in the parasitic process that can be interfered with to achieve nematode control to limit nematode-induced yield losses in crops.Key words: esophageal gland cells, nematode parasitism, parasitome, parasitism genes, secretion.Secredos em secreções: genes tque controlam o parasitismo de nematóides de plantas: As mais avançadas adaptações evolucionárias para o parasitismo de plantas por nematóides são os produtos dos genes de parasitismo expressos nas células da sua glândula esofagial e secretados através do estilete no tecido do hospedeiro, com a finalidade de controlar o complexo processo de parasitismo. Análises moleculares de genes de parasitismo de nematóides têm revelado a complexidade das ferramentas que os permitem atacar as plantas e também obter uma visão mais elaborada do que antes se tinha por hipótese, dos eventos celulares do hospedeiro sob controle específico do parasita. Interessantemente, a maioria dos genes de parasitismo de nematóides descobertos, codificam proteínas específicas para nematóides parasitas de plantas. Identificar o parasitoma do nematóide, isto é, o perfil completo dos produtos dos genes de parasitismo secretados através do estilete durante o ciclo parasítico, é a chave para a compreensão da base molecular do parasitismo de nematóides de plantas. Este conhecimento permitirá identificar os pontos vulneráveis no processo parasítico que podem sofrer interferência, a fim de se controlar o nematóide e limitar as perdas de produção que eles causam em plantas cultivadas.Palavras-chave: células da glândula esofogial, genes de parasitismo, parasitoma, parasitismo de nematóides, secreção.

Go Where the Science Leads You

“…The secretory effector proteins in root-knot nematodes evolved to enable the parasite to regulate, directly or indirectly, specific host genes to reprogram normal root cells for the formation of the specialized giant-cells. The genes expressed in the esophageal gland cells encoding secretory effector proteins with a direct role in parasitism have been termed parasitism genes (21,51).…”

PERSPECTIVES ONPLANT ANDSOILNEMATOLOGY

“…These events are most striking in the elaborate feeding cells that are induced by the nematode infective juveniles and are their sole food source. A number of molecular approaches are being utilized to address genes and gene expression in the nematode feeding sites (17,18,33,41,47,49). This encompasses ongoing investigations on nematode parasitism genes as well as modified host-gene functions.…”

“…This encompasses ongoing investigations on nematode parasitism genes as well as modified host-gene functions. As extensive treatments of this ongoing research are available (33,37,47,49,90), only a few examples of recent developments follow.…”

“…Thus, an ancient relative of the bacterial-feeding C. elegans, lacking the genes required for parasitizing plants, may have acquired cellulases, pectinases, and possibly other genes for parasitism from bacteria-eventually giving rise to root-knot, cyst, and other plant parasites. Still, recent findings suggest that nematodes have evolved their own set of tools to enable them to parasitize plants (41,47,49). A fascinating recent discovery related to nematode parasitism genes is the large number of candidate parasitism genes that encode novel proteins.…”

Resistance of sweet potato clones to meloidogyne incognita races 1 and 3

“…To sustain feeding, nematodes drastically convert the susceptible host root cells into elaborate feeding cells, including complex nodulation, changes in cell gene expression, physiology, morphology and function (Hussey et al, 2002). Parasitism reflections may be the most varied, ranging from root necrosis to nutrient absorption and translocation alterations (Marino et al, 2012), and the most common symptom is root-knot formation at various sizes and shapes.…”