Abstract

The participation of reactive oxygen species (ROS) and nitric oxide (NO), and also enzymatic systems generating them, in the development of heat resistance of wheat (Triticumaestivum L.) seedlings, induced by the hydrogen sulfide (H₂S) donor sodium hydrosulfide (NaHS), has been studied. It was found that 24-h pretreatment of seedlings with 0.1–1 mM NaHS increased their survival after the subsequent 10-min damaging heating at 45°C. The content of hydrogen peroxide and nitric oxide increased together with the nitrate reductase (NR) activity in the seedling roots within the first 4 h of their treatment with the H₂S donor. The rise in the NO level significantly suppressed by the inhibitor of NR sodium tungstate but not the inhibitor of NO synthase (N^G-nitro-L-arginine methyl ester, L-NAME). The hydrogen peroxide scavenger dimethylthiourea (DMTU) and the NADPH oxidase inhibitor imidazole abolished the increase in NR activity and NO content in the roots. However, the nitric oxide scavenger (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, PTIO) and the inhibitors of the NO-producing enzymes only weakly influenced the increase in H₂O₂ content caused by the root treatment with sodium hydrosulfide. The NaHS-induced rise in the seedling heat resistance was eliminated by both ROS antagonists (DMTU and imidazole) and NO antagonists (PTIO and tungstate). It is concluded that the boost in the wheat seedling heat resistance, which is caused by exogenous hydrogen sulfide, is mediated by the increased ROS generation, followed by NR activation, and resultant rise in the level of nitric oxide produced by this enzyme.

中文翻译：

---

硫化氢供体诱导小麦幼苗耐热性过程中ROS与一氧化氮的功能相互作用

摘要

活性氧（ROS）和一氧化氮（NO）以及产生它们的酶系统参与硫化氢（H ₂ S）供体诱导的小麦（Triticum aestivum L.）幼苗耐热性的发展已经研究了硫化氢钠（NaHS）。结果发现，在随后的45°C破坏性加热10分钟后，用0.1–1 mM NaHS预处理种子的24小时可提高其存活率。在用H ₂ S供体处理的前4小时内，幼苗根中的过氧化氢和一氧化氮含量与硝酸根还原酶（NR）活性一起增加。NR钨酸钠抑制剂可显着抑制NO水平升高，但NO合酶抑制剂（N^G-硝基-L-精氨酸甲酯，L-NAME）。过氧化氢清除剂二甲基硫脲（DMTU）和NADPH氧化酶抑制剂咪唑消除了根部NR活性和NO含量的增加。然而，一氧化氮清除剂（2-苯基-4,4,5,5-四甲基咪唑啉-1-氧基1-3氧化物，PTIO）和产生NO的酶的抑制剂仅微弱地影响H ₂ O ₂的增加氢硫化钠根处理引起的含量。NaHS诱导的幼苗耐热性的提高被ROS拮抗剂（DMTU和咪唑）和NO拮抗剂（PTIO和钨酸盐）消除。结论是外源性硫化氢引起的小麦幼苗耐热性的提高是由ROS产生增加，随后的NR活化以及由此酶产生的一氧化氮水平升高所介导的。