Native Arbuscular Mycorrhizal Fungi enhance drought resilience and growth of Amygdalus arabica seedlings in semi-arid regions

Arbuscular mycorrhizal fungi (AMF) play a crucial role in enhancing plant drought tolerance and are key to improving the establishment and survival of tree seedlings in challenging semi-arid environments. Given the consistently low survival rates of Amygdalus arabica Olivier seedlings, this study aimed to elucidate the role of native AMF in enhancing their growth and resistance to water limitation. Rhizosphere soil and root samples were collected from A. arabica in the Zagros forests of western Iran, used for the morphological and molecular identification of native AMF as well as their cultivation. A. arabica seedlings were then inoculated with single-species (Septoglomus deserticola) and multi-species AMF inocula and subjected to three water limitation levels (100%, 60%, and 30% water-holding capacity). Plant growth parameters, physiological indicators, and biochemical stress markers were assessed. Results showed that AMF inoculation significantly enhanced plant growth, improved chlorophyll and antioxidant enzyme activity, and reduced oxidative damage. Multi-species AMF inoculation generally provided greater benefits than single-species inoculation. High root colonization indicated a strong mycorrhizal dependency. These findings confirm the crucial role of AMF symbiosis, driven by enhanced root exploration and a strengthened antioxidant defense system, in promoting plant growth and drought resilience. This study supports the integration of native AMF inoculation into nursery production protocols as a biologically sound strategy to enhance the drought resilience and establishment success of A. arabica seedlings. By improving early-stage seedling physiology under water limitation, native mycorrhizal inoculation may reduce replanting costs and contribute to more efficient afforestation in semi-arid regions, although field validation and soil-level assessments remain essential next steps.