Morphology of arbuscular mycorrhizas is influenced by fungal identity

There are two main morphological types of arbuscular mycorrhizas (AM), the Arum-type and the Paris-type. It is often accepted that AAA morphology is controlled by plant identity. In this experiment the influence of fungal identity on the morphology of AM was investigated. Wild-type (76R) tomato (Lycopersicon esculentum) was grown in association with six different AM fungal species in nurse pots. The morphology of the AM was assessed quantitatively using the magnified intersects technique. Three of the fungal species (Glomus intraradices, G. mosseae, G. versiforme) formed the Arum-type, with characteristic intercellular hyphae and arbuscules. The remaining three species (Gigaspora margarita, Glomus coronatum, and Scutellospora calospora) formed the Paris-type, with hyphal and arbusculate coils. The results demonstrate that the morphology of AM is not solely under plant control but is also influenced by fungal identity. Possible reasons for the differences observed and the functional implications are discussed.