Belowground volatiles facilitate interactions between plant roots and soil organisms

Abstract

Many interactions between organisms are based on the emission and perception of volatiles. The principle of using volatile metabolites as communication signals for chemo-attractant or repellent for species-specific interactions or mediators for cell-to-cell recognition does not stop at an apparently unsuitable or inappropriate environment. These infochemicals do not only diffuse through the atmosphere to process their actions aboveground, but belowground volatile interactions are similarly complex. This review summarizes various eucaryotes (e.g., plant (roots), invertebrates, fungi) and procaryotes (e.g., rhizobacteria) which are involved in these volatile-mediated interactions. The soil volatiles cannot be neglected anymore, but have to be considered in the future as valuable infochemicals to understand the entire integrity of the ecosystems.

Óleo de eucalipto e Pisolithus microcarpus no crescimento de bracatinga em solo contaminado por cobre

“…Entretanto, metabólicos essenciais extraídos de espécies que formam associação com esses fungos podem contribuir para a ocorrência da simbiose em espécies nas quais, em condições naturais, não se tem detectado a ocorrência dessa associação . Conforme Wenke et al (2010) compostos exsudatos pelas raízes das plantas atuam como sinais bioquímicos essenciais. Referidos sinais estimulam a fase pré-simbiótica entre as raízes das plantas e os fungos (Steffen et al, 2011).…”

The Role of Root-Produced Volatile Secondary Metabolites in Mediating Soil Interactions

“…With the exception maybe of agricultural pests such as the larvae of various root flies feeding on cabbage, carrot and onion (Johnson and Gregory 2006;Blossey and Hunt-Joshi 2003), and root lesion nematodes Pratylenchus spp. (Potter et al 1999), little attention has been paid to the role of secondary metabolites as defences against belowground feeding herbivores (Rasmann et al 2011;van Dam 2009), and how this might shape soil communities (Wenke, Kai, and Piechulla 2010;Bais et al 2006). Roots contain an equally rich variety of plant secondary metabolites as shoots do.…”

Characterization of Volatile Organic Compounds Emitted by Barley (Hordeum vulgare L.) Roots and Their Attractiveness to Wireworms

“…Nevertheless, it probably acts as a general signal or a search trigger. Moreover, chemically-mediated orientation due to volatile or non-volatile compounds of the rhizosphere often is proposed whenever root location by subterranean insects is investigated (Johnson and Gregory 2006;Reinecke et al 2008;,Weissteiner et al 2012;Wenke et al 2010). Such cues could be considered within an integrated management perspective, which will never be the case for CO 2 which is present in all soils.…”

“…aboveground plant insect interactions (Effmert et al 2012;Johnson et al 2009;Soler et al 2012;Wenke et al 2010); however, the belowground VOCs potentially responsible for such interactions have to date been partially neglected, due to technical limitations. The release of root VOCs can mediate various interactions: direct or indirect defense of roots against herbivores (Ali et al 2011;Rasmann et al 2005Rasmann et al , 2012a, plant -plant competition (Ens et al 2009;Jassbi et al 2010;Viles and Reese 1996), resistance of roots against pathogens (Cobb et al 1968;Kalemba et al 2002;Vilela et al 2009), and symbiotic interactions (Asensio et al 2012;Paavolainen et al 1998).…”

“…The release of root VOCs can mediate various interactions: direct or indirect defense of roots against herbivores (Ali et al 2011;Rasmann et al 2005Rasmann et al , 2012a, plant -plant competition (Ens et al 2009;Jassbi et al 2010;Viles and Reese 1996), resistance of roots against pathogens (Cobb et al 1968;Kalemba et al 2002;Vilela et al 2009), and symbiotic interactions (Asensio et al 2012;Paavolainen et al 1998). Root derived compounds can also attract herbivores (Wenke et al 2010), and their emission tends to decrease in unattacked conditions (Piesik et al 2011b), thus limiting the energy costs incurred by their synthesis (Herms and Mattson 1992;Rasmann et al 2012a, b). Carbon dioxide gradients are an ubiquitous belowground herbivore attractant, but other volatile and non-volatile semiochemicals also are involved in directing herbivores towards roots (Johnson and Nielsen 2012;Reinecke et al 2008;Weissteiner et al 2012).…”