Ca2+ Participates in H2S Induced Cr6+ Tolerance in Setaria italica

Hydrogen sulfide (H2S), as the third gasotransmitter after nitric oxide (NO) and carbon monoxide (CO), is attracting more and more attentions by the reason of regulating the growth and development process and stress responses in plants. Calcium (Ca2+) has been regarded as a core transducer and regulator in many adaptation processes of plants. In this study, the foxtail millet (Setaria italica), which has considerable tolerance to various stresses, was employed to explore the interaction between HES and Ca2+ signaling in responding to Cr6+ stress. The results showed that Cr6+ stress significantly activated the endogenous HaS generation system. Correspondingly, cell damage from Cr6+ stress was alleviated by exogenous H2S pretreatment but further aggravated by HES synthesis inhibitor hydroxylamine (HA). Meanwhile, under normal conditions, exogenous H/S regulated the expression of Ca2+ signaling downstream molecules coding genes, while the emission of endogenous H2S was also heightened by Ca2+. Further results demonstrated that H2S and Ca2+ improved the Cr6+ tolerance by adjusting the heavy metal ion transporters.