Iron is an essential nutrient for all plants. However, terrestrial plants often suffer from
iron deficiency in alkaline soil due to its extremely low solubility. Alkaline soil accounts for about 30% of all cultivated ground in the world. Plants have evolved two distinct strategies, I and II, for
iron uptake from the soil. Dicots and non-graminaceous monocots use Strategy I, which is primarily based on the reduction of
iron(III) to
iron(II) and the uptake of
iron(II) by the
iron-regulated transporter, IRT1. In contrast, graminaceous plants use Strategy II to efficiently acquire insoluble
iron(III). Strategy II comprises the synthesis and secretion of
iron-chelating phytosiderophores, such as mugineic
acids and the Yellow Stripe 1 transporter
proteins of the
iron(III)-phytosiderophore complex. Barley, which exhibits the highest tolerance to
iron deficiency in alkaline soil among graminaceous plants, utilizes mugineic
acids and the specific
iron(III)-mugineic
acids transporter, HvYS1. In this study, we established the transgenic plant Petunia hybrida, which originally had only Strategy I, by introducing the HvYS1 transporter gene derived from barley. When the transgenic plants were grown hydroponically in media containing the iron(III)-2'-deoxymugineic
acid complex, free
2'-deoxymugineic acid and its
iron(III) complex were detected in the root extract of the transgenic plant by electrospray ionization-Fourier transform-ion
cyclotron resonance mass spectrometry. The growth of the transgenic petunia was significantly better than that of the control host in alkaline conditions. Consequently, the transgenic plant acquired a significantly enhanced tolerance to alkaline hydroponic media in the presence of the iron(III)-2'-deoxymugineic
acid complex. Furthermore, the flower color of the transgenic plant deepened. The results showed that
iron-phytosiderophore complexes and their transporters can potentially be utilized to overcome the worldwide
iron uptake problems to diverse plant species that are found in areas with alkaline conditions.