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

BACKGROUND: Hydrogen sulphide (H(2)S) is involved in regulating physiological processes in plants. We investigated how H(2)S 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 H(2)S role in regulating Fe availability in soybean seedlings. RESULTS: Our results showed that H(2)S completely prevented leaf interveinal chlorosis and caused an increase in soybean seedling biomass under Fe deficiency conditions. Moreover, H(2)S 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, H(2)S 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 H(2)S-mediated alleviation of Fe deficiency in soybean seedlings. CONCLUSION: Our results indicated that Fe deficiency was alleviated by H(2)S through enhancement of Fe acquisition and assimilation, thereby regulating plant hormones and organic acid synthesis in plants.