The contribution of hydrogen sulphide (H₂S) to salicylic acid (SA) induced lead (Pb) stress tolerance modulated by the ascorbate-glutathione (AsA-GSH) cycle was examined in pepper (Capsicum annuum L.) plants. One week after germination, pepper seedlings were sprayed with 0.5 mM SA once a day for a week. Thereafter, seedlings were grown under control (no Pb) or Pb stress (Pb-S treatment consisting of 0.1 mM PbCl₂) for a further 2 weeks. Lead stress reduced plant growth and leaf water status as well as the activities of dehydroascorbate reductase and monodehydroascorbate reductase. However, lead stress elevated leaf Pb, the proline contents, oxidative stress, activities of glutathione reductase and ascorbate peroxidase, as well as the endogenous H₂S content. Supplements of SA resulted in improvements in growth parameters, biomass, leaf water status and AsA-GSH cycle-related enzyme activities, as well as increasing the H₂S content. The positive effect of SA was further enhanced when sodium hydrosulphide was added. However, 0.1 mM hypotaurine (HT) treatment reversed the beneficial effect of SA by reducing the plant H₂S content. Application of NaHS in combination with SA + HT suppressed the adverse effect of HT mainly by restoring the plant H₂S content, suggesting that higher H₂S content, induced by exogenous SA supply, resulted in elevated regulation of the AsA-GSH cycle.

中文翻译：

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水杨酸诱导的硫化氢通过提高抗坏血酸-谷胱甘肽循环提高辣椒植物的铅胁迫耐受性

在辣椒 ( Capsicum annuum L.) 植物中检测了硫化氢 (H ₂ S) 对水杨酸 (SA) 诱导的由抗坏血酸-谷胱甘肽 (AsA-GSH) 循环调节的铅 (Pb) 胁迫耐受性的贡献。发芽一周后，每天一次用 0.5 mM SA 喷洒辣椒幼苗，持续一周。此后，幼苗在对照（无 Pb）或 Pb 胁迫（由 0.1 mM PbCl ₂组成的 Pb-S 处理）下再生长2 周。铅胁迫降低了植物生长和叶片水分状态以及脱氢抗坏血酸还原酶和单脱氢抗坏血酸还原酶的活性。然而，铅胁迫提高了叶片 Pb、脯氨酸含量、氧化应激、谷胱甘肽还原酶和抗坏血酸过氧化物酶的活性，以及​​内源 H ₂S 内容。SA 补充剂可改善生长参数、生物量、叶片水分状况和 AsA-GSH 循环相关酶活性，并增加 H ₂ S 含量。添加硫氢化钠后，SA的积极作用进一步增强。然而，0.1 mM 亚牛磺酸 (HT) 处理通过降低植物 H ₂ S 含量逆转了 SA 的有益作用。_{NaHS 与 SA + HT 的组合应用主要通过恢复植物 H 2} S 含量来抑制 HT 的不利影响，这表明由外源 SA 供应诱导的更高 H ₂ S 含量导致 AsA-GSH 循环的调节增加。