A holistic approach to plant biology

What is it about?

‘Holobiont’ is a term used to describe an organism plus its various microbial hangers-on. It is now widely accepted that just like humans and other animals, plants live in symbiotic relationships with whole assemblages of microbes, which often play roles in major functions such as nutrition. HOW ARE PLANT MICROBIOTA ACQUIRED? Plants are host to an array of microbes that colonise both their above- and below-ground components. In the soil, these tiny organisms can colonise the plant via its roots, and different species can be found on both the inside and the outside of the roots, including perhaps the most well-known plant symbionts, the mycorrhizal fungi. In recent years, studies have also revealed a wealth of life inhabiting leaves, despite their exposed position compared to roots. IS THERE A ‘CORE’ MICROBIOTA? There have been attempts to test the ‘core’ microbiota inhabiting plants, but the results depend on the definition of ‘core’, which could for example refer to a whole species, or just to a population. Initial efforts have been based on both species compositions and functions within the host, and the paper’s authors suggest a more relaxed definition of ‘core’ in order to achieve a pan-microbiome analysis. A QUESTION OF CONTROL Understanding what controls what within the plant holobiont is a nuanced issue with many different components. A host plant might be manipulating certain microbes to improve its fitness, while at the same time being exploited by others. To fully comprehend these interactions, it will be necessary to conduct experiments in which the plant immune system and other aspects are modulated.

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