Fungal volatiles emitted by members of the microbiome of desert plants are diverse and capable of promoting plant growth

Fungi represent a group of eukaryotic microorganisms that are an important part of the plant microbiome. They produce a vast array of metabolites, including fungal volatile organic compounds (fVOCs). However, the diversity and biological activities of fVOCs emitted by the mycobiota of plants native to arid and semi-arid environments remain under-explored. We characterized the chemical diversity of fVOCs produced by 22 representative members of the microbiome of agaves and cacti using SPME-GC-MS. We further tested the effects of pure compounds on the growth and development of Arabidopsis thaliana and host plants. Members of the Sordariomycetes (nine strains), Eurotiomycetes (three), Dothideomycetes (eight), Saccharomycetes (one) and Mucoromycetes (one) were included in our study. We identified 94 fungal organic volatiles classified into nine chemical classes. Terpenes showed the greatest chemical diversity, followed by alcohols and aliphatic compounds. We discovered that camphene and benzyl benzoate, together with the widely distributed and already tested benzyl alcohol, 2-phenylethyl alcohol and 3-methyl-1-butanol, improved plant growth and development of A. thaliana, Agave tequilana and Agave salmiana. Our studies on the fungal VOCs from desert plants underscore an untapped chemical diversity with promising biotechnological applications.