# Bioprospecting and mode of action of volatile organic compounds from morphospecies of the endophytic fungus Hypoxylon anthochroum in the field of bioherbicides

## TL;DR

This study investigates how volatile organic compounds (VOCs) from the endophytic fungus Hypoxylon anthochroum can act as bioherbicides by inhibiting plant growth and mitochondrial function.

## Contribution

The study identifies specific VOCs and their mixtures from Hypoxylon anthochroum that show strong bioherbicidal activity and explores their mode of action on plant mitochondria.

## Key findings

- VOCs from Hypoxylon anthochroum significantly inhibit seed germination, root growth, and seedling respiration in several weed plants.
- Mixtures of VOCs show higher phytotoxicity than individual compounds, with alcohol mixtures being more effective than terpene mixtures.
- VOCs disrupt mitochondrial respiration and membrane potential in isolated M. sativa mitochondria.

## Abstract

In the present investigation, we explore the bioherbicidal activity of seven selected organic compounds (VOCs), previously identified as constituents of mixtures from four Hypoxylon anthochroum endophytic morphospecies. VOCs included four alcohols and three monoterpenes: 3-methyl-1-butanol, 2-methyl-1-butanol, 2-methyl-1-propanol and 2-phenylethanol, and eucalyptol, ocimene and terpinolene. Individual VOCs or VOCs’ mixtures exhibit strong bioherbicidal potential demonstrated through their phytotoxic effect on four herbaceous weed plants and one aquatic plant. VOCs demonstrated a significant inhibitory effect on the seed germination, root growth, and seedling respiration of four common herbaceous plants, including Amaranthus hypochondriacus, Trifolium pratense, Medicago sativa and Panicum miliaceum. In general, root growth was the most affected physiological process across all species, and A. hypochondriacus was the most affected. VOCs’ mixtures exhibit higher activity than pure compounds, at the same time, total mixture (Mtotal; 7 VOCs) and the alcohol mixture (Malcohol; 4 VOCs) demonstrated greater bioherbicidal potential than terpene mixture (Mterpene; 3 VOCs). In addition, we study the mode of action and mechanisms of phytotoxicity of VOCs evaluated on basal mitochondrial respiration and on the integrity or permeability of the mitochondrial membrane. In general, individual VOCs and VOCs’ mixtures have the potential to disrupt cellular respiration and mitochondrial membrane potential of intact mitochondria isolated from M. sativa seedlings. Once again, VOCs’ mixtures exhibit higher phytotoxicity on respiration and mitochondrial membrane potential than pure compounds, at the same time, Mtotal and Malcohol present higher activity than Mterpene. Finally, individual VOCs or VOCs’ mixtures showed phytotoxic effect on the aquatic plant Lemna gibba. Monoterpenes and VOCs’ mixtures proves to be the most effective. VOCs were proved to be promising candidates for the development of bioherbicides with specific targets of action.

• Endophytic fungus Hypoxylon anthochroum produces phytotoxic VOCs.

• VOCs inhibit basal oxygen consumption rate in isolated M. sativa mitochondria.

• Individual VOCs or VOCs’ mixtures altered the mitochondrial membrane potential.