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

Background: 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. Multidisciplinary approaches including physiological, biochemical and molecular, and transcriptome methods were used to investigate the H₂S role in regulating Fe availability in soybean seedlings.

Results: Our 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.

Conclusion: Our 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.

Keywords: Hydrogen sulphide (H2S); Iron assimilation; Iron deficiency; Organic acid; Plant hormones; Soybean (Glycine max).