Differential Strategies of Two Arbuscular Mycorrhizal Fungi Varieties in the Protection of Lycium ruthenicum under Saline–Alkaline Stress

Abstract

To delve into the growth and physiological adaptations exhibited by the economically vital black wolfberry (Lycium ruthenicum) upon inoculation with arbuscular mycorrhizal fungi (AMF) under varying levels of saline–alkaline stress A series of pot experiments were conducted in a gradient saline–alkaline environment (0, 200, 400 mM NaCl: NaHCO3 = 1:1). One-year-old cuttings of black wolfberry, inoculated with two AMF species—Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri)—served as the experimental material, enabling a comprehensive analysis of seedling biomass, chlorophyll content, antioxidant enzyme activities, and other crucial physiological parameters. This study demonstrated that both Fm and Ri could form a symbiotic relationship with the root of Lycium ruthenicum. Notably, Fm inoculation significantly bolstered the growth of the underground parts, while exhibiting a remarkable capacity to scavenge reactive oxygen species (ROS), thereby effectively mitigating membrane oxidative damage induced by stress. Additionally, Fm promoted the accumulation of abscisic acid (ABA) in both leaves and roots, facilitating the exclusion of excess sodium ions from cells. Ri Inoculation primarily contributed to an enhancement in the chlorophyll b (Chlb) content, vital for sustaining photosynthesis processes. Furthermore, Ri’s ability to enhance phosphorus (P) absorption under stressful conditions ensured a steady influx of essential nutrients. These findings point to different strategies employed for Fm and Ri inoculation. To holistically assess the saline–alkaline tolerance of each treatment group, a membership function analysis was employed, ultimately ranking the salt tolerance as Fm > Ri > non-mycorrhizal (NM) control. This finding holds paramount importance for the screening of highly resilient Lycium ruthenicum strains and offers invaluable theoretical underpinnings and technical guidance for the remediation of saline–alkaline soils, fostering sustainable agricultural practices in challenging environments.