# Drought resistance of Argania spinosa L. colonized by the arbuscular mycorrhizal fungus Rhizophagus irregularis varies according to accession

## TL;DR

This study shows that colonizing argan trees with a specific fungus improves their drought resistance, but the benefit varies depending on the tree variety.

## Contribution

The study reveals that mycorrhization benefits argan tree accessions differently under drought stress.

## Key findings

- Mycorrhization improved biomass, root length, and nutrient uptake in all accessions under well-watered conditions.
- Under drought, Mejji and Tidzi accessions showed better stress tolerance and lower oxidative damage compared to City Hanchan.
- AMF colonization significantly enhanced drought resistance in argan trees, with accession-specific responses observed.

## Abstract

Rhizophagus irregularis MUCL 41833 on three argan (Argania spinosa L. Skeels) accessions (Tidzi, Mejji, and City Hanchan) under well-watered (100% field capacity) and water-stressed (15% field capacity) conditions. Whatever the water regime, AMF colonization was observed in all accessions, but Tidzi showed significantly higher total root colonization than City Hanchan, while Mejji showed intermediate levels. Under well-watered conditions, the colonized plants exhibited higher biomass, root length, chlorophyll content, stomatal conductance, and root potassium (K) concentration in all accession. In the Mejji accession, colonized plants also had significantly higher shoot concentrations of phosphorus (P) and K. Under water-stressed conditions, plant response varied with accession. Compared to their respective controls, Mejii had significantly higher biomass, shoot K concentration, chlorophyll content, stomatal conductance, and reduced oxidative stress, Tidzi had also significantly higher biomass, root P and K concentration, and chlorophyll content with lower oxidative stress, while City Hanchan had significantly higher biomass and root P concentration but had higher H2O2 concentration. We can conclude that mycorrhization benefits all three accessions under stress conditions, with the Mejji and Tidzi accessions responding more favorably than the City Hanchan accession. These results highlight the role of AMF in improving argan tree performance under water-limiting conditions and demonstrate the variability in response between accessions.

Flowchart showing the contribution of the arbuscular mycorrhizal fungus Rhizophagus irregularis on argan plants of the accessions Tidzi (TD), Mejjii (MJ), and City Hanchan (CH) plants under well-watered and water-stressed conditions. Parameters such as biomasses, root length, nutrient concentrations, chlorophyll content, and stomatal conductance are increased in well-watered conditions. Under water stress, mycorrhizal plants of the TD and MJ accessions show a decrease in hydrogen peroxide, malondialdehyde (MDA), proline, and total soluble sugars (TSS). A symbol represents arbuscular mycorrhizal fungi (AMF) involvement. Green arrows indicate increases, red arrows denote decreases.