School of Life Science, Liaoning University, Shenyang, 110036, China.
BMC Plant Biol. 2023 Feb 2;23(1):73. doi: 10.1186/s12870-023-04089-y.
Cadmium (Cd) is a highly toxic element for plant growth. In plants, hydrogen sulfide (HS) and methylglyoxal (MG) have emerged as vital signaling molecules that regulate plant growth processes under Cd stress. However, the effects of sodium hydrosulfide (NaHS, a donor of HS) and MG on Cd uptake, physiological responses, and gene expression patterns of Salix to Cd toxicity have been poorly understood. Here, Salix matsudana Koidz. seedlings were planted in plastic pot with applications of MG (108 mg kg) and NaHS (50 mg kg) under Cd (150 mg kg) stress.
Cd treatment significantly increased the reactive oxygen species (ROS) levels and malondialdehyde (MDA) content, but decreased the growth parameters in S. matsudana. However, NaHS and MG supplementation significantly decreased Cd concentration, ROS levels, and MDA content, and finally enhanced the growth parameters. Cd stress accelerated the activities of antioxidative enzymes and the relative expression levels of stress-related genes, which were further improved by NaHS and MG supplementation. However, the activities of monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR) were sharply decreased under Cd stress. Conversely, NaHS and MG applications restored the MDHAR and DHAR activities compared with Cd-treated seedlings. Furthermore, Cd stress decreased the ratios of GSH/GSSG and AsA/DHA but considerably increased the HS and MG levels and glyoxalase I-II system in S. matsudana, while the applications of MG and NaHS restored the redox status of AsA and GSH and further improved glyoxalase II activity. In addition, compared with AsA, GSH showed a more sensitive response to exogenous applications of MG and NaHS and plays more important role in the detoxification of Cd.
The present study illustrated the crucial roles of HS and MG in reducing ROS-mediated oxidative damage to S. matsudana and revealed the vital role of GSH metabolism in regulating Cd-induced stress.
镉（Cd）是一种对植物生长具有高度毒性的元素。在植物中，硫化氢（HS）和甲基乙二醛（MG）已成为重要的信号分子，可调节 Cd 胁迫下植物的生长过程。然而，对于 HS 的供体硫氢化钠（NaHS）和 MG 对 Cd 吸收、生理响应以及 Cd 毒性对柳树基因表达模式的影响，我们知之甚少。在这里，将 Cd（150mg/kg）施加到 Cd 胁迫下的 108mg/kg MG 和 50mg/kg NaHS 处理的银柳（Salix matsudana Koidz.）幼苗的塑料盆中。
Cd 处理显著增加了活性氧（ROS）水平和丙二醛（MDA）含量，但降低了银柳的生长参数。然而，NaHS 和 MG 的补充显著降低了 Cd 浓度、ROS 水平和 MDA 含量，并最终提高了生长参数。Cd 胁迫加速了抗氧化酶的活性和与胁迫相关基因的相对表达水平，而 NaHS 和 MG 的补充则进一步提高了这些水平。然而，单脱氢抗坏血酸还原酶（MDHAR）和脱氢抗坏血酸还原酶（DHAR）的活性在 Cd 胁迫下急剧下降。相反，NaHS 和 MG 的应用恢复了与 Cd 处理幼苗相比，MDHAR 和 DHAR 的活性。此外，Cd 胁迫降低了 GSH/GSSG 和 AsA/DHA 的比值，但大大增加了 HS 和 MG 水平和糖氧还蛋白 I-II 系统在银柳中的含量，而 MG 和 NaHS 的应用恢复了 AsA 和 GSH 的氧化还原状态，并进一步提高了糖氧还蛋白 II 活性。此外，与 AsA 相比，GSH 对外源应用 MG 和 NaHS 表现出更敏感的反应，在 Cd 解毒中发挥更重要的作用。
本研究说明了 HS 和 MG 在减轻 ROS 介导的银柳氧化损伤中的重要作用，并揭示了 GSH 代谢在调节 Cd 诱导的胁迫中的重要作用。
