Belowground plant–microbe communications via volatile compounds

Abstract

Volatiles play important roles in rhizosphere biological communications and interactions. The emission of plant and microbial volatiles is a dynamic phenomenon affected by several endogenous and exogenous signals. Volatile diffusion can be limited by their adsorption, degradation, and dissolution under specific environmental conditions. Therefore, rhizosphere volatiles need to be investigated on a micro and spatiotemporal scale. Plant and microbial volatiles can expand and specialize the rhizobacteria niche not only by improving the root system architecture, as a rich shelter, but also by inhibiting or promoting the growth, chemotaxis, survival, and robustness of neighboring organisms. Root volatiles play an important role in engineering the belowground microbiome by shaping the microbial community structure and recruiting beneficial microbes. Microbial volatiles are appropriate candidates for improving plant growth and health during environmental challenges and climate change. However, some technical and experimental challenges limit the non-destructive monitoring of volatile emissions in the rhizosphere in real-time. In this review, we attempt to clarify the volatile-mediated intra- and inter-kingdom communications in the rhizosphere, and propose improvements in experimental design for future research.

Volatile organic compounds emitted by Burkholderia pyrrocinia CNUC9 trigger induced systemic salt tolerance in Arabidopsis thaliana

“…Root system architecture is coordinated by plant growth hormones including auxin and cytokinin ( Wang et al, 2021 ; Rivas et al, 2022 ); previous studies reported that beneficial soil microbes directly regulate the accumulation of these hormones in plant roots ( Wu et al, 2012 ; Wang et al, 2021 ). Interestingly, volatiles released by PGPR also significantly improve root architecture through modulating the root hormonal networks that contribute to water and nutrient uptake capacity ( Wang et al, 2006 ; Sharifi et al, 2021 ). We observed adverse effects of salt stress on A. thaliana root system architecture in terms of significantly reduced lateral root numbers and root hair development, as well as decreased root length and surface area ( Figure 3 ).…”

Antifungal activity of the volatile organic compounds produced by Ceratocystis fimbriata strains WSJK-1 and Mby

“…New research demonstrates that microorganisms emit VOCs that trigger robust plant systemic defense responses against pathogenic ( Tahir et al, 2017 ; Sharifi and Ryu, 2018 ; Sharifi et al, 2022 ). According to molecular studies, systemic defense responses occur due to an increase in the concentration of metabolites and defense-related enzymes such as phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO; Wu et al, 2019a ; Hata et al, 2021 ; Messa, 2021 ).…”

Volatile organic compounds shape belowground plant–fungi interactions

“…Acton et al (2018) measured VOCs by using airflow generated in a root glass chamber filled with a potting substrate. All belowground VOCs emitted to the environment in a certain time can be measured by proton transfer reaction mass spectrometry (PTR-MS) (Majchrzak et al, 2018;Tholl et al, 2021;Sharifi et al, 2022).…”