Infochemicals in terrestrial plants and seaweed holobionts: current and future trends

Abstract

Since the holobiont concept came into the limelight ten years ago, we have become aware that responses of holobionts to climate change stressors may be driven by shifts in the microbiota. However, the complex interactions underlying holobiont responses across aquatic and terrestrial ecosystems remain largely unresolved. One of the key factors driving these responses is the infochemicalmediated communication in the holobiont. In order to come up with a holistic picture, in this Viewpoint we compare mechanisms and infochemicals in the rhizosphere of plants and the eco-chemosphere of seaweeds in response to climate change stressors and other environmental stressors, including drought, warming and nutrient stress. Furthermore, we discuss the inclusion of chemical ecology concepts that are of crucial importance in driving holobiont survival, adaptation and/or holobiont breakdown. Infochemicals can thus be regarded as a 'missing link' in our understanding of holobiont response to climate change and should be investigated while investigating the responses of plant and seaweed holobionts to climate change. This will set the basis for improving our understanding of holobiont responses to climate change stressors across terrestrial and aquatic ecosystems.

Rhizosphere Microbial Communities and Heavy Metals

“…Essential in electron transport chain; cofactor of many enzymes; involved in photosynthesis and chlorophyll synthesis [22].…”

“…Plants can be considered metaorganisms with close relationships with their associated microorganisms [ 21 ]. Indeed, according to the holobiont theory, hosts, such as plants and their microbiome, are symbionts [ 19 , 22 ]. Plant life is closely linked to key microbes, which can influence several aspects of plant ecology, such as growth, germination, biotic and abiotic stress resistance and fitness [ 19 , 21 , 22 ].…”

“…Indeed, according to the holobiont theory, hosts, such as plants and their microbiome, are symbionts [ 19 , 22 ]. Plant life is closely linked to key microbes, which can influence several aspects of plant ecology, such as growth, germination, biotic and abiotic stress resistance and fitness [ 19 , 21 , 22 ]. This theory suggests which host-microbiome relationships evolve over time, not just during a single host lifetime, but also through a coevolutionary process, leading to very complex relationships in microorganism-root systems [ 23 ].…”

Editorial: Chemically Mediated Interactions Between Marine Macrophytes and Microbes

“…We do not know which infochemicals facilitate or inhibit the preferential attachment of macrophytes by microbes senso lato (i.e., including photosynthetic microalgae and cyanobacteria and heterotrophic bacteria), whether the selected macroalgae can stimulate the production of particular phycotoxins, whether microbes produce compounds (and if so, which chemicals) that act as deterrent of macrophytes grazing. Given the important role that the rapidly undergoing climate-driven changes (rising temperature, acidification, hypoxia, desalination) are playing in the aquatic ecosystems, potential modifications on such chemically mediated interactions (Schmidt and Saha, 2020) cannot be discarded. Identifying infochemicals and understanding their role have been challenging mainly by technical limitation.…”

Chemically Mediated Microbial “Gardening” Capacity of a Seaweed Holobiont Is Dynamic

“…Rich in infochemicals, a seaweed's surface layer can be considered as a marketplace where cross-kingdom communications are mediated by release and uptake of metabolites. This zone has been recently defined as "eco-chemosphere" of seaweeds [14]. The diverse chemical milieu from the surface can be composed of sugars, fatty acids, amino acids, and other secondary and primary metabolites [15][16][17][18].…”