Fe deficiency is a major challenge that limits agricultural productivity and is a serious human health concern worldwide. Under iron-limiting conditions soil microorganisms produce siderophores, that chelates Fe3+ (ferric) and make it available to the plants. Selection of efficient siderophore producing bacteria and establishing their role in enhancing iron uptake is a strategic approach for improving plant nutrition. Hence 3 efficient isolates Pantoea agglomerans, Pseudomonas plecoglossida and Lactococcus lactis, selected from a repository of 154 bacteria, producing catecholate, hydroxamate and carboxylate siderophores, respectively, were assessed for Fe chelation efficiency using 59Fe and their role in plant biometric parameters, Fe uptake and antioxidant enzymes with tomato (Strategy I) and wheat (Strategy II) test plants under hydroponic system. Cell-free siderophore preparation (Sid) improved plant parameters and iron nutrition more efficiently than bacterial inoculants. Pantoea agglomerans was proven best as its 59Fe-bound siderophore complex showed the highest uptake of 4.25 and 1.59 Bq plant-1 in wheat and tomato, respectively. Further, the Fe-starved plants (1 µm Fe-EDTA) showed around two-fold higher 59Fe uptake than those raised under Fe-sufficient condition (100 µm Fe-EDTA). Results indicated that probably the bacterial mediated iron translocation in plants is Strategy III, complementing both Strategy I and II by facilitating higher availability of chelated Fe to plant reductases directly and/or through ligand exchange with phytosiderophores, respectively. This study highlights the need for integration of siderophore based formulations in INM strategies for enhancing plant iron content to address the Fe deficiency challenge of the soil and human nutrition.

中文翻译：

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化学型铁载体产生细菌对植物铁营养贡献的放射化学证据。

铁缺乏是限制农业生产力的主要挑战，也是世界范围内严重的人类健康问题。在铁限制条件下，土壤微生物产生铁载体，螯合 Fe3+（三价铁）并使其可用于植物。选择有效的铁载体产生细菌并确定它们在增强铁吸收方面的作用是改善植物营养的战略方法。因此，从 154 种细菌的储存库中选出的 3 种有效分离株 Pantoea agglomerans、Pseudomonas plecoglossida 和 Lactococcus lactis，分别产生儿茶酚酸盐、异羟肟酸盐和羧酸盐铁载体，使用 59Fe 评估 Fe 螯合效率及其在植物生物特征参数中的作用，番茄（策略 I）和小麦（策略 II）在水培系统下测试植物的铁吸收和抗氧化酶。无细胞铁载体制剂 (Sid) 比细菌接种剂更有效地改善了植物参数和铁营养。Pantoea agglomerans 被证明是最好的，因为其 59Fe 结合的铁载体复合物在小麦和番茄中分别显示出最高的 4.25 和 1.59 Bq plant-1 吸收。此外，缺乏铁的植物 (1 µm Fe-EDTA) 的 59Fe 吸收量比在铁充足条件下种植的植物 (100 µm Fe-EDTA) 高约两倍。结果表明，植物中细菌介导的铁易位可能是策略 III，通过促进螯合铁直接和/或通过与植物铁素体的配体交换来提高螯合铁对植物还原酶的可用性，从而补充策略 I 和 II。