Iron deficiency conditions as well as iron supplied as a Fe(III)-mimosine complex induced a number of strategy I and strategy II genes for iron uptake in leucaena. Leucaena leucocephala (leucaena) is a tree-legume that can grow in alkaline soils, where metal-cofactors like Fe(III) are sparingly available. Mimosine, a known chelator of Fe(III), may facilitate Fe(III) uptake in leucaena by serving as a phytosiderophore. To test if mimosine can serve as a phytosiderophore, three sets of experiments were carried out. First, the binding properties and solubility of metal-mimosine complexes were assessed through spectrophotometry. Second, to study mimosine uptake in plants, pole bean, common bean, and tomato plants were supplied with mimosine alone and metal-mimosine complexes. Third, the expression of strategy I (S1) and strategy II (S2) genes for iron uptake from the soil was studied in leucaena plants exposed to different Fe(III) complexes. The results of this study show that (i) mimosine has high binding affinity for metallic cations at alkaline pH, Fe(III)-mimosine complexes are water soluble at alkaline pH, and that mimosine can bind soil iron under alkaline pH; (ii) pole bean, common bean, and tomato plants can uptake mimosine and transport it throughout the plant; and (iii) a number of S1 and S2 genes were upregulated in leucaena under iron-deficiency condition or when Fe(III) was supplied as a Fe(III)-mimosine complex. These findings suggest that leucaena may utilize both S1 and S2 strategies for iron uptake; and mimosine may play an important role in both strategies.

中文翻译：

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含羞草碱通过形成含羞草碱-阳离子复合物促进植物对金属阳离子的吸收。

缺铁条件以及作为 Fe(III)-含羞草素复合物供应的铁诱导了许多策略 I 和策略 II 基因用于银合欢中的铁摄取。Leucaena leucocephala (leucaena) 是一种豆科植物，可以在碱性土壤中生长，在这种土壤中，Fe(III) 等金属辅助因子很少见。Mimosine 是一种已知的 Fe(III) 螯合剂，可作为植物铁载体促进银合欢中的 Fe(III) 吸收。为了测试含羞草素是否可以作为植物铁载体，进行了三组实验。首先，通过分光光度法评估金属-含羞草素复合物的结合特性和溶解度。其次，为了研究植物中含羞草碱的吸收，向豆类、普通豆类和番茄植物单独提供含羞草碱和金属-含羞草碱复合物。第三，在暴露于不同 Fe(III) 配合物的银合欢植物中研究了从土壤中吸收铁的策略 I (S1) 和策略 II (S2) 基因的表达。本研究结果表明：(i)含羞草碱在碱性pH下对金属阳离子具有高结合亲和力，Fe(III)-含羞草碱配合物在碱性pH下具有水溶性，含羞草碱在碱性pH下可与土壤铁结合；(ii) 极豆、普通豆和番茄植物可以吸收含羞草素并将其运输到整个植物中；(iii) 在缺铁条件下或当 Fe(III) 作为 Fe(III)-mimosine 复合物提供时，银合欢中的许多 S1 和 S2 基因上调。这些发现表明银合欢可以利用 S1 和 S2 策略来吸收铁。和 mimosine 可能在这两种策略中都发挥重要作用。