Stop and smell the fungi: Fungal volatile metabolites are overlooked signals involved in fungal interaction with plants

Abstract

Diverse fungi are intimately associated with plants, and molecules secreted from both the plant and fungal sides play critical roles in the establishment of their associations and affect plant growth and health. Through evolutionary arms races or strategic alliances with plants, fungi and other microbes have invented a bewildering array of secreted molecules to parasitize or communicate with plants. Research empowered by omics data and tools has greatly advanced understanding of the nature, role and mechanism of action of many secreted fungal proteins that affect plants directly or indirectly. However, available information about fungal volatile metabolites with similar functions is quite limited. Through this review, we aim to stimulate expeditions to this vastly under-explored frontier of fungal chemical ecology.

Do volatile compounds produced by Fusarium oxysporum and Verticillium dahliae affect stress tolerance in plants?

“…Besides affecting growth and development, VCs produced by some microbes seem to function as elicitors for ISR (Bitas et al 2013; Farag et al 2013; Song and Ryu 2013; Chung et al 2016; Li et al 2016). To evaluate if VCs produced by F. oxysporum and V. dahliae also affect plant defence signalling, we employed two A. thaliana transgenic lines containing PR1::GUS and PDF 1.2::GUS , respectively.…”

“…In return, microbes may receive nutrients and better protected ecological niche. Recently, a number of studies suggested the role of microbial VCs in improving plant’s ability to manage different types of stress, including drought, salinity and pathogen infection (Ortíz-Castro et al 2009; Bailly and Weisskopf 2012; Bitas et al 2013; Farag et al 2013; Kanchiswamy et al 2015; Chung et al 2016; Li et al 2016; Piechulla et al 2017). Here, we showed that VCs produced by soilborne fungal pathogens F. oxysporum and V. dahliae also help A. thaliana growth better in the presence of salt.…”

“…Besides increased salt tolerance, VCs produced by some bacteria and fungi also have been shown to elicit induced systemic resistance (ISR), a defence mechanism that protects plants from diverse pathogens (Bitas et al 2013; Farag et al 2013; Song and Ryu 2013; Chung et al 2016; Li et al 2016). For example, 1-octen-3-ol, a VC commonly produced by fungi, induced the expression of several defence-related genes in A. thaliana , and upon inoculation with Botrytis cinerea disease, symptom was less severe in 1-octen-3-ol-treated plants than control plants (Kishimoto et al 2007).…”

“…For example, 1-octen-3-ol, a VC commonly produced by fungi, induced the expression of several defence-related genes in A. thaliana , and upon inoculation with Botrytis cinerea disease, symptom was less severe in 1-octen-3-ol-treated plants than control plants (Kishimoto et al 2007). More examples of microbial VCs as potential elicitors for ISR were reviewed by Bitas et al (2013) and Li et al (2016). …”

Smelly Fumes: Volatile-Mediated Communication between Bacteria and Other Organisms

“…Already at the very start of this research field, it became apparent that several microbial volatiles can modulate plant growth and have both plant growth-promoting and disease-suppressing activities (Ryu et al, 2003(Ryu et al, , 2004Bailly and Weisskopf, 2012;Li et al, 2016). In this special issue, two papers describe the role of fungal volatiles on plant growth and defense (Bitas et al; Kottb et al): Bitas and colleagues studied volatile-mediated signaling between fungi and plants using a nonpathogenic Fusarium oxysporum and Arabidopsis thaliana as model organisms.…”