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Aims: Plants on coastal sand dunes are subjected to strong environmental fluctuations which affect their growth and survival. Sea water invasion of the dunar zone caused by storms is an important factor that determines the persistence of a plant community. In the present study, the benefits of arbuscular mycorrhiza on psammophilic plant species subjected to sea water flooding episodes were evaluated under controlled conditions and the effect of sea water on in vitro spore production was determined. Methods: In a greenhouse experiment, the growth response of nine plant species to inoculation with Glomus intraradices in beach sand was evaluated. A second experiment was designed in order to test if plant survival under sea water flooding was influenced by the symbiosis. A third experiment was conducted in vitro to quantify the effect of sea water on the production of G. intraradices spores. Results: Glomus intraradices was effective in promoting plant growth and survival in beach sand and promoted the survival of some species subjected to flooding events. Spore production was inhibited by 50% of sea water in the growth media, but not by 10% sea water. Conclusions: Results obtained under controlled conditions indicated that arbuscular mycorrhiza can improve the establishment of certain dune plant species in beach sand as the symbiosis contributes to enhanced plant tolerance against occasional sea water flooding. [ABSTRACT FROM AUTHOR]