Hydrogen sulphide improves adaptation of Zea mays seedlings to iron deficiency.

Juan Chen,Hai-Lei Zheng,Yu-Ting Shang,Martin Simon,Zhou-Ping Shangguan,Wen-Hua Wang,Wen-Jun Hu,Xiang Liu,Fei-Hua Wu

doi:10.1093/jxb/erv368

Abstract

Hydrogen sulphide (H2S) is emerging as a potential molecule involved in physiological regulation in plants. However, whether H2S regulates iron-shortage responses in plants is largely unknown. Here, the role of H2S in modulating iron availability in maize (Zea mays L. cv Canner) seedlings grown in iron-deficient culture solution is reported. The main results are as follows: Firstly, NaHS, a donor of H2S, completely prevented leaf interveinal chlorosis in maize seedlings grown in iron-deficient culture solution. Secondly, electron micrographs of mesophyll cells from iron-deficient maize seedlings revealed plastids with few photosynthetic lamellae and rudimentary grana. On the contrary, mesophyll chloroplasts appeared completely developed in H2S-treated maize seedlings. Thirdly, H2S treatment increased iron accumulation in maize seedlings by changing the expression levels of iron homeostasis- and sulphur metabolism-related genes. Fourthly, phytosiderophore (PS) accumulation and secretion were enhanced by H2S treatment in seedlings grown in iron-deficient solution. Indeed, the gene expression of ferric-phytosiderophore transporter (ZmYS1) was specifically induced by iron deficiency in maize leaves and roots, whereas their abundance was decreased by NaHS treatment. Lastly, H2S significantly enhanced photosynthesis through promoting the protein expression of ribulose-1,5-bisphosphate carboxylase large subunit (RuBISCO LSU) and phosphoenolpyruvate carboxylase (PEPC) and the expression of genes encoding RuBISCO large subunit (RBCL), small subunit (RBCS), D1 protein (psbA), and PEPC in maize seedlings grown in iron-deficient solution. These results indicate that H2S is closely related to iron uptake, transport, and accumulation, and consequently increases chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants.

Highlights

Iron is an essential nutrient for various cellular and physi- fundamental biochemical processes, such as respiration, ological processes in plants
These results indicate that H2S is closely related to iron uptake, transport, and accumulation, and increases chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants
The chlorophyll content under GSH treatment increased, but not by as much as the NaHS-induced increases. These results showed that H2S rather than other sulphur-containing compounds or sodium was responsible for the increase in chlorophyll content in iron-deficient maize plants

Summary

Introduction

Iron is an essential nutrient for various cellular and physi- fundamental biochemical processes, such as respiration, ological processes in plants It functions as a component of photosynthesis, oxygen transport, and so on (Graziano and many important enzymes and proteins that are involved in Lamattina, 2007). Iron uptake and translocation are controlled by many components which have been recently characterized at the molecular level (Schmidt, 1999), it is not known how signalling molecules are involved in the response of plants to iron deficiency. Some evidence has been provided that CO, as an endogenous gaseous molecule, may play an important role in improving plant adaptation to iron deficiency (Kong et al, 2010) It is still not clear whether a low concentration of H2S, similar to that of NO and CO, is involved in the regulation of iron assimilation and availability in plants. The total content of non-protein thiols (NPTs) in maize seedlings was measured according the Del Longo et al (1993) with minor modifications

Materials and methods

Results

Discussion