Phytobiome

A phytobiome consists of a plant (phyto) situated in its specific ecological area (biome), including its environment and the associated communities of organisms which inhabit it.

Recent metagenomic and metatranscriptomic approaches have allowed scientists to discover novel taxonomic species that are not easily cultured in a laboratory.

[5] There are numerous physical and chemical signals such as secreted lipids, peptides and polysaccharides that allow organisms to recognize and interact within the phytobiome.

Bacteria are known to produce quorum sensing molecules such as homoserine lactones, lipid-like diffusable factors and signaling peptides that mediate plant-bacteria interactions such as colonization.

[5] In addition to plant-bacterial interactions, bacteria often secrete bactericidal or fungicidal compounds into the phytobiome to reduce local competition for niches and resources.

[9] Insects communicate to transfer information regarding external threats, social status, food availability and mating through the production of volatile pheromones, also known as semiochemicals.

[5] Many plant species have evolved production of volatile chemicals that interfere with pheromone signaling, often through inhibition of proper olfactory neuron function.

[5] The production of these exudates is heavily influenced by environmental factors and plant physiology and can alter the community composition of the rhizosphere and rhizoplane.

[5] The secretion of flavonoids helps to recruit Rhizobia bacteria that form a mutualistic symbiosis with numerous plant species.

[12] In addition, many phytohormones that function in abiotic stress tolerance or plant growth also trigger responses with the microbial community.

The production of salicylic acid in Arabidopsis was shown to influence the root microbiome composition by acting as a signal or carbon source.