Curie C, Panaviene Z, Loulergue C, Dellaporta S L, Briat J F, Walker E L
Biochimie et Physiologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Montpellier 2 et Ecole Nationale Supérieure d'Agronomie, France.
Nature. 2001 Jan 18;409(6818):346-9. doi: 10.1038/35053080.
Frequently, crop plants do not take up adequate amounts of iron from the soil, leading to chlorosis, poor yield and decreased nutritional quality. Extremely limited soil bioavailability of iron has led plants to evolve two distinct uptake strategies: chelation, which is used by the world's principal grain crops; and reduction, which is used by other plant groups. The chelation strategy involves extrusion of low-molecular-mass secondary amino acids (mugineic acids) known as 'phytosiderophores' which chelate sparingly soluble iron. The Fe(III)-phytosiderophore complex is then taken up by an unknown transporter at the root surface. The maize yellow stripe1 (ys1) mutant is deficient in Fe(III)-phytosiderophore uptake, therefore YS1 has been suggested to be the Fe(III)-phytosiderophore transporter. Here we show that ys1 is a membrane protein that mediates iron uptake. Expression of YS1 in a yeast iron uptake mutant restores growth specifically on Fe(III)-phytosiderophore media. Under iron-deficient conditions, ys1 messenger RNA levels increase in both roots and shoots. Cloning of ys1 is an important step in understanding iron uptake in grasses, and has implications for mechanisms controlling iron homeostasis in all plants.
农作物常常无法从土壤中吸收足够的铁，从而导致黄化、产量低下和营养品质下降。土壤中铁的生物有效性极其有限，这使得植物进化出两种不同的吸收策略：螯合作用，世界主要谷类作物采用这种策略；还原作用，其他植物类群采用这种策略。螯合策略包括分泌低分子量的次生氨基酸（ mugineic 酸），即所谓的“植物铁载体”，它能螯合难溶性铁。然后， Fe(III)-植物铁载体复合物通过根表面一种未知的转运蛋白被吸收。玉米黄条纹 1 （ ys1 ）突变体在 Fe(III)-植物铁载体吸收方面存在缺陷，因此有人认为 YS1 是 Fe(III)-植物铁载体转运蛋白。我们在此表明， ys1 是一种介导铁吸收的膜蛋白。 YS1 在酵母铁吸收突变体中的表达能特异性地恢复在 Fe(III)-植物铁载体培养基上的生长。在缺铁条件下， ys1 信使核糖核酸水平在根和芽中都会增加。 ys1 的克隆是了解禾本科植物铁吸收的重要一步，对控制所有植物铁稳态的机制具有重要意义。
