Hydrogen sulfide and proline cooperate to alleviate cadmium stress in foxtail millet seedlings

Abstract Hydrogen sulfide (H 2 S) and some functional amino acids in crops have been involved in the defense system against heavy - metal pollution. Here we report the relationships and functions of H 2 S and proline to cadmium (Cd) stress. Sodium hydrosulfide (NaHS) pretreatment decreased the electrolytic leakage and the malondialdehyde and hydrogen peroxide contents while enhancing photosynthesis in Cd - treated seedlings. Furthermore, pretreatment with NaHS markedly exacerbated Cd - induced alterations in proline content, the activities of proline - 5 - carboxylate reductase (P5CR) and proline dehydrogenase (PDH), and the transcript levels of P5CR and PDH. When endogenous H 2 S was scavenged or inhibited by various H 2 S modulators, the Cd-induced increase in endogenous proline was weakened. Combined pretreatment with H 2 S and proline was moderately higher in the Cd-stressed growth status, stomata movements and oxidative damage of seedlings compared to a single treatment with H 2 S or proline. These results suggest that H 2 S and proline cooperate to alleviate Cd - damage in foxtail millet.