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RESEARCH PRODUCT

Arbuscular mycorrhiza induced ATPases and membrane nutrient transport mechanisms

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description

The evolutionary success of arbuscular mycorrhizal (AM) symbiosis reflects the unique combination of a superior biotrophic mode of fungal carbon acquisition and the ability of the living plant to absorb nutrients, especially phosphorus, from the fungal partner (Jakobsen 1999). This mutualistic way of life must require controlled expression of a large set of membrane transport systems active in phosphate uptake from the soil by the extraradical hyphae, its transfer to the host plant across a symbiotic interface, and coupled to transport of photosynthates in the opposite direction. The implied membrane transporters are therefore integral systems in the functioning of the symbiosis. Very little is as yet known of the mechanisms which determine the controlled nutrient exchange between partners at the symbiotic interfaces. Membrane transport proteins responsible for movement of phosphate and carbon compounds across the individual plant and fungal membranes at the symbiotic interfaces have not so far been identified. However, increasing information about plasma membrane H+-ATPases, a family of enzymes that drive active secondary transport systems, is being obtained from the use of molecular biology and cytology techniques. In this chapter, we summarize current knowledge on plant and fungal plasma membrane ATPases and discuss their possible implication in transport mechanisms operating at the membranes of both symbionts in arbuscular mycorrhiza.