Hydrogen sulfide (H2 S) is a newly recognized molecule mediating plant defense responses under drought. The role of exogenous H2 S in regulating plant responses under drought has been reported in a few plant species including spinach, wheat, Arabidopsis, soybean, and citrus plants. However, no report is available on the outcome of exogenous H2 S on drought response in safflower plants. Therefore, the present study was planned to get insight into H2 S-mediated regulation of growth, secondary metabolism, oxidative defense and uptake of minerals in two safflower cultivars (Safflower-16427 and Safflower-16493). Plants were exposed to two NaHS (0.5 and 1.0 mM) and two drought levels (70 and 50% field capacity (FC)). We found a notable depression in growth, yield, chlorophyll, and potassium (K+ ) uptake under drought. The decline was more significant in plants facing 50% FC. The oxidative injury in plants was higher under severe drought and lead to the decline in chlorophyll, plant biomass and yield production. Drought induced a noticeable accretion in the accumulation of total soluble sugars, proline, ascorbic acid, anthocyanins, and secondary metabolites that protect plants against oxidative damages caused by drought. The activities of antioxidant enzymes increased substantially in safflower cultivars under drought. Besides, plants pretreated with NaHS (0.5 mM) subsided the oxidative damage by increasing the accumulation of secondary metabolites and strengthening the antioxidant capacity under drought. Further, drought plants suffered significant disturbances in ions homeostasis that was circumvented by exogenous H2 S. The interactive effect of drought and H2 S did not display a significant difference between the cultivars. This article is protected by copyright. All rights reserved.

中文翻译：

---

硫化氢通过调节干旱条件下的次生代谢、氧化防御和元素吸收来介导红花的防御反应

硫化氢 (H2 S) 是一种新发现的分子，可在干旱条件下调节植物防御反应。据报道，外源 H2 S 在干旱条件下调节植物反应的作用已在菠菜、小麦、拟南芥、大豆和柑橘类植物等少数植物物种中发挥作用。然而，没有关于外源 H2S 对红花植物干旱响应结果的报告。因此，本研究旨在深入了解 H2 S 介导的两个红花品种（Safflower-16427 和 Safflower-16493）中生长、次生代谢、氧化防御和矿物质吸收的调节。植物暴露于两种 NaHS（0.5 和 1.0 mM）和两种干旱水平（70% 和 50% 田间持水量 (FC)）。我们发现干旱条件下生长、产量、叶绿素和钾 (K+) 吸收显着下降。在面临 50% FC 的植物中，下降更为显着。严重干旱对植物的氧化损伤程度更高，导致叶绿素、植物生物量和产量下降。干旱导致可溶性总糖、脯氨酸、抗坏血酸、花青素和次生代谢产物的积累显着增加，这些代谢产物可保护植物免受干旱引起的氧化损伤。干旱条件下红花品种的抗氧化酶活性显着增加。此外，用 NaHS (0.5 mM) 预处理的植物通过增加次生代谢物的积累和增强干旱条件下的抗氧化能力来减轻氧化损伤。此外，干旱植物受到外源 H2 S 规避的离子稳态的显着干扰。干旱和硫化氢的交互作用在不同品种间没有表现出显着差异。本文受版权保护。版权所有。