Physiological responses of two typical desert plants seedlings under salt stress mediated by arbuscular mycorrhizal networks

Arbuscular mycorrhizal fungi (AMF) enhance the stress resistance of desert plants through symbiosis. This study focused on Glycyrrhiza inflata and Lycium ruthenicum, two typical desert plant species from the lower reaches of the Tarim River, and established conspecific (GG) and heterospecific (GL) plant combinations. The plants were treated with NaCl at concentrations of 0, 150, 250, and 350 mmol·L-1. A two-chamber device was used, with donor plants (inoculated with AMF) subjected to salt stress and receptor plants (not inoculated with AMF) kept under nonstress conditions. The experiment measured plant biomass; chlorophyll content; photosynthetic fluorescence parameters; antioxidant enzyme activity; osmotic regulators; and the levels of plant hormones such as abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA). The results were as follows: (1) Salt stress significantly reduced the mycorrhizal infection rate in donor plants (PPPPP<0.05). The receptor plants, which were not under direct salt stress, exhibited synchronized hormonal changes, photosynthetic inhibition (decrease in SPAD and Fv/Fm), photoprotective activation (increase in NPQ), and systemic defense responses (increase in SOD and POD activity and proline and SS accumulation). These changes suggest that donor plants transmit “warning” signals to receptor plants via the common mycorrhizal network (CMN). In the GG combination, the ABA and SA levels were primarily enhanced, which protects the photosynthetic apparatus. In the GL combination, the ABA and JA levels were enhanced-which activated the antioxidant system-but with higher MDA accumulation. This regulatory pattern highlights the central role of CMN in interplant communication and collaborative adaptation to salt stress, providing important theoretical insights into symbiotic mechanisms in desert plants and ecological restoration.