Römheld V, Marschner H
Institut für Pflanzenernährung, Universität Hohenheim, Postfach 700562, D-7000 Stuttgart 70, Federal Republic of Germany.
Plant Physiol. 1983 Apr;71(4):949-54. doi: 10.1104/pp.71.4.949.
Iron deficiency in peanuts (Arachis hypogeae L.) caused an increase in release of caffeic acid, a higher rate of Fe(III) reduction, and increased rates of both Fe(III) chelate splitting and iron uptake.Experiments on Fe(III) reduction by phenolics (in vitro experiments) and by roots of Fe-deficient peanuts exclude the direct involvement of released phenolics in Fe(III) reduction by roots: Fe(III) reduction by phenolics had a pH optimum higher than 8.0 and was strongly dependent on the concentration and the stability of the supplied Fe(III) chelates. In contrast, Fe(III) reduction by roots of Fe-deficient peanuts had a pH optimum of about 5.0 and was less dependent on the stability of the supplied Fe(III) chelates. Furthermore, the observed release of phenolics into nutrient solution would have to be at least 200 times higher to attain the reduction rates of roots of Fe-deficient peanuts. The results of these experiments support the idea of an enzymic reduction of Fe(III) on the plasmalemma of cortical cells of roots.
花生（落花生）缺铁会导致咖啡酸释放增加、Fe(III)还原速率提高以及Fe(III)螯合物分解和铁吸收速率增加。对酚类物质还原Fe(III)（体外实验）以及缺铁花生根系还原Fe(III)的实验排除了释放的酚类物质直接参与根系还原Fe(III)的可能性：酚类物质还原Fe(III)的最适pH高于8.0，并且强烈依赖于所供应的Fe(III)螯合物的浓度和稳定性。相比之下，缺铁花生根系还原Fe(III)的最适pH约为5.0，并且对所供应的Fe(III)螯合物的稳定性依赖性较小。此外，观察到的酚类物质向营养液中的释放量必须至少高出200倍，才能达到缺铁花生根系的还原速率。这些实验结果支持了根系皮层细胞质膜上Fe(III)发生酶促还原的观点。
