Amelioration of Salt Stress on Bermudagrass by the Fungus Aspergillus aculeatus

There is considerable evidence that plant abiotic-stress tolerance can be evoked by the exploitation of a globally abundant microbe. A. aculeatus, which was initially isolated from the rhizosphere of bermudagrass, has been shown to increase heavy metal tolerance in turfgrasses. Here, we report on the potential of A. aculeatus to induce tolerance to salt stress in bermudagrass. Physiological markers for salt stress, such as plant growth rate, lipid peroxidation, photosynthesis, and ionic homeostasis were assessed. Results indicated that strain A. aculeatus produced indole-3-acetic acid (IAA) and siderophores and exhibited a greater capacity for Na+ absorption under salt stress. The plant inoculation by A. aculeatus increased plant growth and attenuated the NaCl-induced lipid peroxidation in roots and leaves of bermudagrass. The fungus significantly elevated the amount of IAA and glutathione and slightly enhanced photosynthetic efficiency of salt-treated bermudagrass. Tissues of inoculated plants had significantly increased concentrations of K+ but lower Na+ concentrations than those of uninoculated regimes. It appears that the role of A. aculeatus in alleviating bermudagrass salt stress is partly to produce IAA, to increase the activity of anti-oxidases, to absorb Na+ by fungal hyphae, and to prevent the plant from ionic homeostasis disruption.