The effect of colonization with the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol.& Gerd.) Gerdemann & Trappe on the growth and physiology of NaCl-stressed maize plants ( Zea mays L. cv. Yedan 13) was examined in the greenhouse. Maize plants were grown in sand with 0 or 100 mM NaCl and at two phosphorus (P) (0.05 and 0.1 mM) levels for 34 days, following 34 days of non-saline pre-treatment. Mycorrhizal plants maintained higher root and shoot dry weights. Concentrations of chlorophyll, P and soluble sugars were higher than in non-mycorrhizal plants under given NaCl and P levels. Sodium concentration in roots or shoots was similar in mycorrhizal and non-mycorrhizal plants. Mycorrhizal plants had higher electrolyte concentrations in roots and lower electrolyte leakage from roots than non-mycorrhizal plants under given NaCl and P levels. Although plants in the low P plus AM fungus treatment and those with high P minus AM fungus had similar P concentrations, the mycorrhizal plants still had higher dry weights, soluble sugars and electrolyte concentrations in roots. Similar relationships were observed regardless of the presence or absence of salt stress. Higher soluble sugars and electrolyte concentrations in mycorrhizal plants suggested a higher osmoregulating capacity of these plants. Alleviation of salt stress of a host plant by AM colonization appears not to be a specific effect. Furthermore, higher requirement for carbohydrates by AM fungi induces higher soluble sugar accumulation in host root tissues, which is independent of improvement in plant P status and enhances resistance to salt-induced osmotic stress in the mycorrhizal plant.

Salt stress is one of the most important stresses that affect coastal vegetation. A halophyte Carex pumila plays a crucial role in the maintenance of fragile ecosystems in coastal areas. Thus, understanding the mechanism of C. pumila responses to salt stress is a prerequisite for the conservation and utilization of this species. After treatment with 200, 300, 400, 500 mM NaCl for 60 h, C. pumila leaves displayed a decline in the relative water content and an increase in salt injury index. Osmolyte accumulation, as a function of osmotic adjustment, and antioxidant enzyme activities were maintained under salinity, even at a high NaCl concentration. High NaCl concentrations severely affected the photosystem II, the JIP-test indicated a significant decrease in performance indexes and quantum efficiencies and an increase in phenomenological fluxes. Metabolic analyses showed the changes of 39 metabolites, including 16 kinds of organic acids, 9 kinds of amino acids, 9 kinds of sugars, 3 kinds of sugar alcohols, and 2 amines. The identified metabolites were mainly involved in the glycolysis, pentose phosphate pathway, and tricarboxylic acids cycle.