LAUSR

Salt stress is restricting crop productivity worldwide, especially in arid and semiarid areas. The plants in salinized areas have various strategies to adapt to salt stress, including forming mutual symbiosis with arbuscular mycorrhizal fungi (AMF). Due to the ubiquity of AMF in terrestrial ecosystem and their performance in aiding host plant to face to the environmental challenge, they can be a potential facilitator for reclaiming salinized soils. Plants inhabiting in salinized soils suffer from structural damage due to osmotic and oxidative pressure induced by salt stress, however, the role of AMF played in the ultrastructural changes of host plants is less clear. Lycium barbarum (Goji) is a tree species with medicinal value which usually suffers from salt stress. Here we investigated the impacts of inoculating Diversispora versiformis on the ultrastructure and chlorophyll fluorescence of mesophyll cells of Goji under salt stress. The extent of plasmolysis in mesophyll cells of Goji inoculated with D. versiformis was lower compared with control under 200 mmol/L NaCl. The chloroplasts of non-mycorrhizal Goji were swollen, with distorted thylakoids and large gap between chloroplast membrane and plasma membrane under salt stress. However, mycorrhizal Goji had integrated chloroplast and well organized grana, the gap between chloroplast membrane and plasma membrane was smaller than control under salt stress. Concurrently, the chlorophyll fluorescence performance of mycorrhizal Goji suffered less than non-mycorrhizal Goji under 200 mmol/L NaCl. Collectively, our results demonstrate that AMF could confer higher salt tolerance to Goji through protecting the ultrastructure and photochemical activity.