A synthetic phytosiderophore analog, proline-2′-deoxymugineic acid, is efficiently utilized by dicots

Abstract

Purpose Phytosiderophores (PS) from grasses solubilize sparingly soluble iron (Fe), and the resultant PS-Fe is an Fe source even for dicots. Recently, the synthetic PS proline-2′-deoxymugineic acid (PDMA) has been developed as a moderately biodegradable Fe fertilizer for grasses. We aimed to investigate whether PDMA-Fe is also a good Fe source for dicots. Methods The availability of PDMA-Fe to cucumber was evaluated in a calcareous substrate and hydroponic cultures at pH 7.0–9.0 by determining chlorophyll level, PSII activity, and Fe uptake. EDDHA-Fe, EDTA-Fe, and citrate-Fe were used as controls. The reducibility of Fe chelates by roots was measured to determine the mechanism underlying differences in availability. Expressions of Fe deficiency-inducible genes were analyzed to estimate the Fe status in plants. Results The application of PDMA-Fe and EDDHA-Fe to a calcareous substrate reduced Fe-deficient chlorosis to a similar extent; however, the shoot Fe concentration was higher in the PDMA-Fe treatment. In the hydroponic culture, the availability of PDMA-Fe was higher than that of the other chelates at all pH levels, and this was confirmed by higher PSII activity and lower expression of Fe deficiency-inducible genes. The reducibility assay revealed that the reduction level of PDMA-Fe was greater than that of EDTA-Fe and citrate-Fe under alkaline pH. Conclusions PDMA-Fe is utilized by cucumber roots more efficiently than traditional synthetic chelates in both calcareous substrate and hydroponic cultures. The higher availability of PDMA-Fe may be attributed to its higher reducibility. Our findings suggest that PDMA-Fe could be a good Fe fertilizer for dicots.

The active Fe chelator proline‐2′‐deoxymugineic acid enhances peanut yield by improving soil Fe availability and plant Fe status

“…The growth of the PDMAtreated peanut plants was therefore promoted (Figure 1). Similar results could be found in rice and cucumber (Suzuki et al, 2021;Ueno et al, 2021). Importantly, our work produces the novel finding that PDMA can increase the yield and kernel micronutrient contents of peanuts (Table 1, Figure 6), implying the great ability of PDMA to improve the production and quality of plants under Fe-limited field conditions.…”

“…Recently, PDMA, an effective Fe chelator, was synthesised based on the structure of the phytosiderophore DMA (Suzuki et al, 2021). PDMA, with low synthesis costs and high stability, was proven to improve Fe nutrition in rice and cucumber under conditions of hydroponic culture and calcareous substrates (Suzuki et al, 2021; Ueno et al, 2021). In this study, positive effects of PDMA on Fe nutrition and peanut yields were demonstrated in calcareous soil under field conditions.…”

“…PDMA was synthesised and supplied by the Aichi Steel Corp. (Japan) as described in a previous report (Suzuki et al, 2021). The PDMA-Fe complex was prepared as described in a recent work (Ueno et al, 2021). First, we mixed 2.47 M FeCl 3 with 10 mM PDMA at a ratio of 2:1 and then adjusted the pH to 7.0 with 0.5 M NaOH.…”

“…PDMA is much more stable than DMA, and the cost of synthesis is lower (Kratena et al, 2021; Suzuki et al, 2021). Moreover, PDMA has been shown to improve the Fe nutrition of some plants in hydroponic culture and calcareous substrates (Suzuki et al, 2021; Ueno et al, 2021), thus revealing the great potential of PDMA as a novel biological Fe fertiliser. However, the effect of PDMA on improving the Fe nutrition and yield of crops remains unclear under field conditions.…”

“…Due to the high pH in calcareous soil, the EDTA‐Fe fertiliser is easily fixed in the soil after application. In contrast, PDMA has a greater ability to improve Fe nutrition in rice and cucumber (Suzuki et al, 2021; Ueno et al, 2021). However, the influence and related molecular and ecological mechanisms underlying the effect of PDMA on the Fe nutrition and yield for peanut plants grown in calcareous soil require further investigation.…”