Arbuscular mycorrhizal fungi improve the growth and drought tolerance of Zenia insignis seedlings under drought stress

Drought is one of the most critical limiting environmental factors for plant survival and restoration in areas of rocky desertification in southwestern China. Here, we aimed to understand how arbuscular mycorrhizal fungi (AMF) affect the growth and drought tolerance of tree species used for afforestation, with the ultimate aim of using them to restore degraded karst ecosystems. A pot experiment was conducted in which Zenia insignis seedlings were inoculated separately with three AMF (Funneliformis mosseae, Rhizoglomus intraradices, and Diversispora versiformis) and a mixture of all three species under two water regimes (drought stress and normal water) in a greenhouse. The results showed that AMF have a positive effect on plant biomass, osmolytes, and antioxidant enzyme activity under drought conditions. Shoot/root biomass increased by 12.5-33.8% and plant height increased by 13.6-32.1% after inoculation with AMF under drought conditions. The phosphorus content of the shoots significantly increased in mycorrhized plants, whereas nitrogen content was minimally affected. Superoxide dismutase and catalase activity was higher under drought stress in mycorrhized plants than in non-mycorrhized plants. The same pattern was found for soluble sugar and proline content in mycorrhized seedings under water deficit conditions. Mixed AMF inoculation had a more beneficial effect on plant growth than single AMF inoculation. In conclusion, our results indicate that AMF inoculation could help restore degraded ecosystems in desertified karst regions.