Ecology and Evolution of Soil Nematode Chemotaxis

Abstract

Plants influence the behavior of and modify community composition of soil-dwelling organisms through the exudation of organic molecules. Given the chemical complexity of the soil matrix, soil-dwelling organisms have evolved the ability to detect and respond to these cues for successful foraging. A key question is how specific these responses are and how they may evolve. Here, we review and discuss the ecology and evolution of chemotaxis of soil nematodes. Soil nematodes are a group of diverse functional and taxonomic types, which may reveal a variety of responses. We predicted that nematodes of different feeding guilds use host-specific cues for chemotaxis. However, the examination of a comprehensive nematode phylogeny revealed that distantly related nematodes, and nematodes from different feeding guilds, can exploit the same signals for positive orientation. Carbon dioxide (CO(2)), which is ubiquitous in soil and indicates biological activity, is widely used as such a cue. The use of the same signals by a variety of species and species groups suggests that parts of the chemo-sensory machinery have remained highly conserved during the radiation of nematodes. However, besides CO(2), many other chemical compounds, belonging to different chemical classes, have been shown to induce chemotaxis in nematodes. Plants surrounded by a complex nematode community, including beneficial entomopathogenic nematodes, plant-parasitic nematodes, as well as microbial feeders, are thus under diffuse selection for producing specific molecules in the rhizosphere that maximize their fitness. However, it is largely unknown how selection may operate and how belowground signaling may evolve. Given the paucity of data for certain groups of nematodes, future work is needed to better understand the evolutionary mechanisms of communication between plant roots and soil biota.

Evaluación de arvenses como hospedantes alternos de nematodos fitoparásitos en cafetales en Costa Rica

“…La diferencia en la condición R, T y HPS de acuerdo con el número de NF en suelo y raíz tiene su origen en aspectos de la biología de los nematodos (por ejemplo, el ciclo de vida), y la interacción nematodo-arvense (por ejemplo, el tipo de parasitismo). La densidad de NF en suelo está relacionada con la liberación de sustancias químicas (exudados) a través de las raíces, las cuales constituyen atrayentes de NF hacia la planta (Curtis, 2008;Rasmann et al, 2012;Dong et al, 2014). Este fenómeno podría hacer que una arvense adquiera una condición R o T con base en un número alto de NF en suelo.…”

Host-seeking behavior of the Heterorhabditis amazonensis nematode in response to stimulant sources1

“…Recent evidence has shown that several species of entomopathogenic nematodes have taken advantage of the volatile compounds emitted by plant roots being attacked by insects to locate the insects, even over long distances. Carbon dioxide (CO 2 ) in the soil indicates a biological activity and has been widely implicated in locating a host (Rasmann et al 2012). Turlings et al (2012) reported that the combination of this gas and specific volatile root compounds is more attractive than when encountered individually, acting synergistically to attract entomopathogenic nematodes.…”

Plant-nematode Interactions: From Genomics to Metabolomics

“…2A). This hatching is induced by some stimuli from the soil or from the root exudates of the plants (Hallem et al, 2011;Rasmann et al, 2012). After penetrating into roots, the J2 larvae migrate intercellularly through cortical cells to search out the vascular cylinder.…”