Sodium Chloride Stress Induced Changes in Leaf Osmotic Adjustment of Trifoliate Orange (Poncirus trifoliata) Seedlings Inoculated with Mycorrhizal Fungi

Abstract

Citrus plants are sensitive to salinity, and thus employing new approaches to alleviate salt damage are necessary. The present study evaluated the effect of two arbuscular mycorrhizal fungi (AMF), Glomus mosseae and G. versiforme, on leaf osmotic adjustment of trifoliate orange (Poncirus trifoliata) seedings exposed to 100 mM NaCl. Salinity significantly inhibited mycorrhizal colonization, plant biomass and leaf relative water content, whereas the reduce of plant biomass was notably alleviated by the mycorrhizal colonization. Mycorrhizal seedlings exhibited significantly lower Na+ and Ca2+ concentrations, whilst also recorded higher K+ concentration and K+/Na+, Ca2+/Na+ and Mg2+/Na+ ratios at both salinity levels. Under salinity stress, mycorrhizal symbiosis markedly decreased sucrose concentrations of leaves and also increased glucose, fructose and proline concentrations of leaves. The results suggest that arbuscular mycorrhizas improved leaf osmotic adjustment responses of the seedlings to salt stress, thus enhancing salt tolerance of mycorrhizal plants.