Mycorrhizal benefits on native plants of the Caatinga, a Brazilian dry tropical forest

In the terrestrial ecosystems, soil is an important component, characterized by holding high diversity of microorganisms which play a key role for productivity and vegetal composition. The group of symbionts microorganisms stands out for contributing directly to the growth and plant nutrition, and among them, the arbuscular mycorrhizal fungi form one of the oldest and well established associations. In order to increase the knowledge and contribute for further research with AMF and plants of Caatinga, in this review we compile data from previous studies on the effects of symbiosis between arbuscular mycorrhizal fungi (AMF) and plants of the Caatinga, a type of dry tropical forest found in the northeast of Brazil. These studies collected data under various experimental conditions, emphasizing fungal efficiency and host responsiveness in soils with varied fertility. From our analysis we conclude that in general the symbiotic efficiency on these plants depends on many factors, such as the plant-fungi combination, fertility and soil type. Furthermore, in leguminosae the impact of a joint inoculation with nitrogen fixing bacteria must be taken into account. Claroideoglomus etunicatum was the most tested AMF species benefiting almost all plants tested. Approximately 30 plant species were studied regarding possible benefits provided by AMF and of these only Hymenea courbaril and Aspidosperma pyrifolium did not respond to mycorrhization. Higher efficiency of the mycorrhizal symbiosis can be obtained in soils with low P levels, emphasizing the essential role of these microorganisms in the growth and survival of plant species from the Caatinga biome.