Fungal Volatiles Linked to Root Growth Under Osmotic Stress

Airborne compounds released by symbiotic fungi may influence how plants develop roots when water availability is challenged. Minambres and colleagues investigated these signals in Arabidopsis seedlings exposed to fungal volatiles.

What the study found

In a bioRxiv preprint, the authors exposed seedlings to volatile organic compounds (VOCs) from three symbiotic fungi: Laccaria bicolor, Hebeloma cylindrosporum and Serendipita indica. They report increased lateral root proliferation by day 10 under both control and osmotic-stress conditions.

Gene-expression analysis showed a rapid, temporary increase in activity of auxin transport genes within three days, with little early change in cytokinin-related activity. Tests using plants with altered responses to these hormones led the authors to conclude that the early response bypasses their classic antagonism.

The authors also report changes involving glucosinolate and leucine metabolism and the potassium and iron transporters HAK5 and IRT1. Analyses of mutants and nitric oxide signaling components indicated that potassium transport and nitric oxide-dependent regulation of IRT1 were essential to the developmental response.

Why it matters

The findings suggest that fungal signals can influence root development without physical contact and may help researchers investigate plant responses to osmotic stress. They also connect early hormone-related changes with nutrient transport and signaling pathways.

Limits and unknowns

The abstract does not identify the responsible VOCs, quantify root growth or stress tolerance, or explain how stress tolerance was measured. It also does not provide sample sizes, experimental conditions or results for each fungus separately. The study used Arabidopsis seedlings; the abstract does not establish whether the findings extend to crops or field conditions. As a preprint, the work has not been presented here as peer-reviewed research.

Read the research

Authors: Minambres, E., Fermoso-Dominguez, J., Rodriguez-Sufuentes, S., Marco-Montori, P., Lorenzo, O., Calvo-Polanco, M.

Published: 2026-10-29

Source basis: Based on the abstract only

Original abstract

Symbiotic fungi communicate with plants via volatile organic compounds (VOCs), even before physical contact. While fungal VOCs are known to promote plant development under control conditions, their effects under abiotic stress remain poorly characterized. Here, we exposed Arabidopsis thaliana seedlings to VOCs from the ectomycorrhizal fungi Laccaria bicolor and Hebeloma cylindrosporum, and the endophyte Serendipita indica, under osmotic stress. Time-course transcriptional analysis revealed a rapid, transient induction of auxin transport genes within 3 days of VOC exposure, with minimal early cytokinin modulation. Using auxin- (aux1-7, axr1-3) and cytokinin-resistant (cre1, arr1-4) mutants, we show that this early response bypasses classic auxin/cytokinin antagonism, promoting lateral root proliferation by day 10 under both control and stress conditions. Transcriptomic profiling indicated that fungal VOCs modulate glucosinolate and leucine metabolism and regulate potassium (HAK5) and iron (IRT1) transporters. Genetic and phenotypic analyses of hak5-2 and akt1-2 mutants, together with nitric oxide signaling components, revealed that potassium transport and nitric oxide-dependent IRT1 regulation are essential for translating VOC perception into developmental responses. These findings underscore the multifaceted mechanisms by which fungal VOCs coordinate plant development and abiotic stress tolerance.

This article is an AI-generated adaptation, not a substitute for the original research. Preprints may not have been peer reviewed; AI can make mistakes.