Hydrogen sulphide alleviates iron deficiency by promoting iron availability and plant hormone levels in Glycine max seedlings

Juan Chen,Ni-Na Zhang,Zhouping Shangguan,Jian-Hua Zhang,Xue-Yuan Lin,Qing Pan,Ge-Hong Wei

doi:10.1186/s12870-020-02601-2

Abstract

BackgroundHydrogen sulphide (H2S) is involved in regulating physiological processes in plants. We investigated how H2S ameliorates iron (Fe) deficiency in soybean (Glycine max L.) seedlings. Multidisciplinary approaches including physiological, biochemical and molecular, and transcriptome methods were used to investigate the H2S role in regulating Fe availability in soybean seedlings.ResultsOur results showed that H2S completely prevented leaf interveinal chlorosis and caused an increase in soybean seedling biomass under Fe deficiency conditions. Moreover, H2S decreased the amount of root-bound apoplastic Fe and increased the Fe content in leaves and roots by regulating the ferric-chelate reductase (FCR) activities and Fe homeostasis- and sulphur metabolism-related gene expression levels, thereby promoting photosynthesis in soybean seedlings. In addition, H2S changed the plant hormone concentrations by modulating plant hormone-related gene expression abundances in soybean seedlings grown in Fe-deficient solution. Furthermore, organic acid biosynthesis and related genes expression also played a vital role in modulating the H2S-mediated alleviation of Fe deficiency in soybean seedlings.ConclusionOur results indicated that Fe deficiency was alleviated by H2S through enhancement of Fe acquisition and assimilation, thereby regulating plant hormones and organic acid synthesis in plants.

Highlights

Hydrogen sulphide (H2S) is involved in regulating physiological processes in plants
Strategy I plant species respond to Fe deficiency in at least three steps: (1) the release of protons to acidify the rhizosphere by H+-ATPase, (2) the induction of ferric chelate reductase activity mediated by ferric-chelate reductase (FCR), which catalyses the reduction of ferric iron chelates to Fe2+, and (3) the uptake of Fe2+ by the high-affinity metal transporter iron-regulated transporter1 (IRT1), which is responsible for transporting the Fe2+ into root cells [3, 7, 8]
After 15 d of treatments, the dry weight of leaf, stem and root were strongly enhanced by NaHS in Fe-deficient (−Fe) plants compared with those that had not been treated with NaHS, in contrast to the –Fe plants, where H2S did not affect the dry weight of +Fe plants (Table 1)

Summary

Introduction

Hydrogen sulphide (H2S) is involved in regulating physiological processes in plants. We investigated how H2S ameliorates iron (Fe) deficiency in soybean (Glycine max L.) seedlings. Strategy I plant species (all dicots and non-graminaceous monocots) respond to Fe deficiency in at least three steps: (1) the release of protons to acidify the rhizosphere by H+-ATPase, (2) the induction of ferric chelate reductase activity mediated by ferric-chelate reductase (FCR), which catalyses the reduction of ferric iron chelates to Fe2+, and (3) the uptake of Fe2+ by the high-affinity metal transporter IRT1 (ironregulated transporter 1), which is responsible for transporting the Fe2+ into root cells [3, 7, 8]. Strategy II plant species (graminaceous monocots) respond to Fe deficiency in four steps: (1) phytosiderophore (muginetic acid, MAs) biosynthesis within roots, (2) phytosiderophore (PS) secretion into the rhizosphere, (3) solubilization of insoluble Fe in soils through the chelation of PSs, and (4) uptake of the ferric-phytosiderophore complex by roots [9, 10]

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