Symbiotic interactions between a newly identified native mycorrhizal fungi complex and the endemic tree Argania spinosa mediate growth, photosynthesis, and enzymatic responses under drought stress conditions

Abstract

Argan tree (Argania spinosa skeels) is one of the most affected species by desertification and global warming. To advance knowledge on how this tree can withstand drought stress, Arbuscular mycorrhizal fungi (AMF) inoculation with a native complex, mainly formed of Glomus genus, was studied on a set of growth and physiological parameters. Under controlled conditions, inoculated and non- inoculated Argan seedlings were grown for three months under three water regimes (25%, 50%, 75% relatively to the field capacity of used soil substrate). Results showed that the Argan tree had different growth abilities to develop and withstand the various applied water limitations. The AMF complex stimulates growth and mineral nutrition of Argan seedlings under the different imposed levels of water deficiency). The Relative water content (RWC) in leaves, the hydric potential and the stomatal conductance in Argan leaves had shown a general improvement in inoculated seedlings compared to non-inoculated ones. Soluble sugar and proline contents significantly increased in non-inoculated compared with inoculated seedlings under water-limiting conditions (25%). This was similar to oxidative enzyme (Catalase, peoxydase, superoxide dismutase) whose activity increased significantly in drought stressed seedlings.