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Abstract
Iron (Fe) is an essential nutrient in both plants and humans. Fe deficiency on calcareous soil with low Fe availability is a major agricultural problem. Nicotianamine (NA) is one of the Fe chelator in plants, which is involved in metal translocation into seeds, and serves as an antihypertensive substance in humans. In this study, soybean plants overexpressing the barley NA synthase 1 (HvNAS1) gene driven by the constitutive CaMV 35S promoter were produced using Agrobacterium-mediated transformation. The transgenic soybean showed no growth defect and grew normally. The NA content of transgenic soybean seeds was up to four-fold greater than that of non-transgenic (NT) soybean seeds. The level of HvNAS1 expression was positively correlated with the amount of NA, and a high concentration of NA was maintained in the seeds in succeeding generations. The Fe concentration was approximately two-fold greater in transgenic soybean seeds than in NT soybean seeds. Furthermore, the transgenic soybeans showed tolerance to low Fe availability in calcareous soil. Our results suggested that increasing the NA content in soybean seeds by the overexpression of HvNAS1 offers potential benefits for both human health and agricultural productivity.
Graphical Abstract
NA is plant Fe chelator and has antihypertensive effect in humans. HvNAS1 overexpressed soybean contains large amount of NA and Fe, and showed tolerance to Fe deficiency.
Acknowledgments
We thank Dr Paula Olhoft (University of Minnesota) and Prof. David Sommers (University of Minnesota) for providing us with technical advice and suggestions for soybean transformation. We thank Dr Khurram Bashir and Dr Reiko N. Itai for reading and commenting on the manuscript.
