『Abstract
　Organic acids, such as malate, citrate and oxalate, have been proposed to be involved in many processes operating in the rhizosphere, including nutrient acquisition and metal detoxification, alleviation of anaerobic stress in roots, mineral weathering and pathogen attraction. A full assessment of their role in these processes, however, cannot be determined unless the exact mechanisms of plant organic acid release and the fate of these compounds in the soil are more fully understood. This review therefore includes information on organic acid levels in plants (concentrations, compartmentalisation, spatial aspects, synthesis), plant efflux (passive versus active transport, theoretical versus experimental consideration), soil reactions (soil solution concentrations, sorption) and microbial considerations (mineralization). In summary, the release of organic acids from roots can operate by multiple mechanisms in response to a number of well-defined environmental stresses (e.g., Al, P and Fe stress, anoxia): These responses, however, are highly stress- and plant-species specific. In addition, this review indicates that the sorption of organic acids to the mineral phases and mineralisation by the soil's microbial biomass are critical to determining the effectiveness of organic acids in most rhizosphere processes.』

『要旨
　りんご酸塩、クエン酸塩、およびシュウ酸塩のような有機酸は、栄養の獲得と金属の無毒化、根の嫌気的ストレスの軽減、鉱物風化、および病原体の誘引を含む、根圏に作用する多くの過程に関係していることが提案されてきた。しかし、これらの過程でのそれらの役割を完全に評価することは、植物有機酸の放出の正確なメカニズムおよび土壌中のこれらの化合物の挙動がもっと十分に理解されない限り行えない。そのため、このレビューは、植物における有機酸のレベル（濃度、区画化、空間的様相、合成）、植物流出（受動的対自発的輸送、理論的対実験的考察）、土壌反応（土壌溶液濃度、収着）、および微生物学的考察（鉱化作用）を含んでいる。まとめとして、根からの有機酸の放出は、多数の明確な環境ストレス（たとえば、Al、P、およびFeストレス、酸素欠乏）に応じて多数のメカニズムにより作動することが可能である：しかし、これらの反応は高いストレスの特定の植物種である。くわえて、鉱物相に対する有機酸の収着および土壌微生物による鉱化作用は、大部分の根圏過程における有機酸の有効性を決定するために重大であることを、このレビューは示している。』

Introduction
Organic acids in plants
　Root content
　Root release of organic acids
　Theoretical considerations
　Experimental considerations
　Organic acid release by calciole versus calcifuge plants
　Organic acid release under Fe deficiency
　Organic acid release under phosphorus deficiency
　Role of organic acids in aluminium detoxification
　Organic acid release by roots under other nutrient stresses
　Organic acid release by roots under oxygen stress
Do organic acids cause rhizosphere acidification ?
Organic acids in soil
　Soil solution concentrations
　Metal complexation reactions in the soil solution
　P, Mn and Fe mobilisation
　Organic acid sorption in soils
　Concentration gradients of organic acids in the rhizosphere
　Organic acids in mineral dissolution and pedogenic processes
Impact of the soil microbial biomass on organic acids
Conclusions
Acknowledgements
References