Pseudoarthrobacter BD237 volatile organic compounds promote Brachypodium distachyon growth

Abstract

Microbial volatile organic compounds (mVOCs) present an environmentally sustainable alternative or supplement to traditionally used agrochemicals, such as fertilisers, herbicides and pesticides. Microbial VOCs can promote the growth and stress tolerance of a variety of dicot plants, largely through modulation of phytohormone pathways. However, their effect in monocot plants, particularly grasses, remains largely unexplored. PseudoarthrobacterBD237s mVOCs were assayed for their growth promoting effect in the model cereal, Brachypodium distachyon. BD237 mVOCs were found to significantly increase the dry shoot and root weight of B. distachyon by 25% and 42%, respectively. Gas chromatography analysis showed that BD237 produced a variety of alcohols and ketones. Exposure to pure standards of phenylethyl alcohol and 2-nonanone were found to significantly promote B. distachyon growth. Transcriptome analysis of B.distachyon roots exposed to BD237 mVOC revealed significant upregulation of genes related to photosynthesis and response to abiotic stress. Transcriptome analysis of BD237 plate colonies exposed to B. distachyon VOCs revealed no significant differential transcription, indicating that BD237 VOC production may be constitutive. These results suggest that BD237 mVOCs may promote B. distachyon growth by increasing photosynthetic rate and may increase tolerance to abiotic stressors such as salinity and drought. Collectively, this work expands our understanding of microbe monocot VOC mediated interactions and identifies specific VOCs as potential grass biostimulants.