Iron deficiency results in severe yield losses, particularly in calcareous soils. Recent evidences suggest that biofertilizers with plant growth-promoting rhizobacteria (PGPR) may be an efficient strategy for enhancing iron (Fe) nutrition in legumes. This work aimed at evaluating the capacity of PGPR strains to enhance Fe uptake-related processes in soybean grown in calcareous soil. From the studied 24 PGPR, Sphingobium fuliginis ZR 1–6 and Pseudomonas jessenni ZR 3–8 strains were selected for the inoculation experiment based on their in vitro ability to produce indole-3-acetic acid, 1-aminocyclopropane-1-carboxylic acid deaminase, siderophores, and organic acids, to tolerate high pH, and to reduce Fe³⁺. The effect of bacterial inoculation on improving Fe uptake was tested using each isolate alone or combined and through the evaluation of several morphological, physiological, and molecular parameters. Inoculation with S. fuliginis showed beneficial effects particularly at the root level by the improvement of ferric chelate activity (111%) and FRO2 expression (646%), resulting in increased Fe root content (62%). Inoculation with P. jessenii increased Zn and Mn concentrations in the trifoliates (463% and 51%, respectively), decreased Zn concentration in the roots (88%), and increased the expression of FER4 in the trifoliates (5260%). Combined inoculation of both strains fostered Fe accumulation in the trifoliates and increased the expression of IRT1 and FER4 genes, indicating an improved capacity of Fe translocation to the shoots. These results suggest that inoculation with selected PGPR strains could be effective in improving Fe uptake and accumulation in soybean grown under Fe-deficient conditions.

缺铁会导致严重的产量损失，尤其是在钙质土壤中。最近的证据表明，具有植物促生根瘤菌（PGPR）的生物肥料可能是增强豆类中铁（Fe）营养的有效策略。这项工作旨在评估PGPR菌株增强钙质土壤中种植的大豆中与铁吸收相关的过程的能力。从研究的24个PGPR中，根据它们的体外产生吲哚-3-乙酸，1-氨基环丙烷-1-羧酸脱氨酶的能力，选择了富营养的鞘氨醇单胞菌ZR 1-6和假单胞菌ZR 3-8进行接种实验。，铁载体和有机酸，可耐受高pH值并减少Fe ³⁺。通过单独使用或组合使用每种分离物，并通过评估几种形态，生理和分子参数，来测试细菌接种对改善铁吸收的影响。充分利用S. fuliginis接种显示出有益的效果，特别是在根部，通过改善铁螯合物活性（111％）和FRO2表达（646％），导致铁根含量增加（62％）。接种耶氏疟原虫三叶酸中锌和锰的浓度增加（分别为463％和51％），根中锌浓度降低（88％），三叶酸中FER4的表达增加（5260％）。两种菌株的联合接种促进了铁在三叶中的积累，并增加了IRT1和FER4基因的表达，表明铁向芽的转运能力提高了。这些结果表明，用选定的PGPR菌株接种可有效提高在缺铁条件下生长的大豆中的铁吸收和积累。