外源H2O2对不同水分条件下垂盆草线粒体稳态、生长及品质的调控作用

目的 为揭示外源H₂O₂叶面预处理对不同水分条件下垂盆草Sedum sarmentosum线粒体稳态、生长和黄酮类成分积累的调控作用。方法 设置4个处理即适宜水分、适宜水分＋1 mmol/L H₂O₂、干旱、干旱＋1 mmol/L H₂O₂处理，测定不同处理垂盆草叶肉细胞超微结构及其线粒体抗氧化系统、垂盆草生长指标、生物量、指标性成分含量及多种体外抗氧化能力。结果 在干旱胁迫条件下外源喷施1 mmol/L H₂O₂可以显著提高垂盆草线粒体超氧化物歧化酶（superoxide dismutase，SOD）、过氧化物酶（peroxidase，POD）和抗坏血酸过氧化物酶（ascorbate peroxidase，APX）活性，显著降低线粒体超氧阴离子产生速率及丙二醛（malondialdehyde，MDA）含量，减轻线粒体膜结构破坏。在干旱条件下叶片喷施H₂O₂处理的垂盆草鲜质量和干质量分别比干旱处理提高51.53%和38.78%，总黄酮、总酚含量分别提高13.37%和6.50%，但槲皮素和异鼠李素含量显著低于其他处理。适宜水分条件下喷施H₂O₂处理有利于提高生物量和异鼠李素含量。垂盆草ABTS、DPPH、OH·自由基清除能力与抗脂质过氧化能力均以适宜水分＋喷施H₂O₂处理最高，干旱＋喷施H₂O₂处理次之。结论 喷施1 mmol/L H₂O₂可以缓解干旱胁迫对垂盆草的氧化伤害，维持线粒体稳态，提高垂盆草药材产量和品质，从而协调干旱逆境下垂盆草产量和品质之间的矛盾；适宜水分条件下喷施H₂O₂亦有助于提升垂盆草产量和品质。

Regulation of exogenous H2O2 on mitochondrial homeostasis, growth and quality of Sedum sarmentosum under different water conditions

Objective To reveal the regulatory effects of exogenous H₂O₂ leaf pretreatment on mitochondrial homeostasis, growth and flavonoids accumulation in Sedum sarmentosum under different water conditions. Methods Four treatments were conducted, namely, suitable moisure, suitable moisure + 1 mmol/L H₂O₂, drought, drought + 1 mmol/L H₂O₂. The ultrastructure of mesophyll cells and mitochondrial antioxidant system of S. sarmentosum under different treatments, as well as the growth index, biomass, contents of quality-related components and four in vitro antioxidant capacities of S. sarmentosum were determined. Results Exogenous spraying of 1 mmol/L H₂O₂under drought stress could significantly increase the activities of superoxide dismutase (SOD), perxidase (POD) and ascorbate peroxidase (APX) in mitochondria of S. sarmentosum, significantly reduce the mitochondrial production rate and malondialdehyde (MDA) content, and reduce the damage of mitochondrial membrane structure. Under drought conditions, the fresh weight and dry weight of leaves which sprayed with H₂O₂ increased by 51.53% and 38.78%, and the contents of total flavonoids and total phenols increased by 13.37% and 6.50%, respectively, compared with those under drought conditions, but the contents of quercetin and isorhamnetin were significantly lower than those under other treatments. Spraying H₂O₂ under suitable water condition was conducive to improving biomass and isorhamnetin content. ABTS, DPPH, OH· radical scavenging ability and anti-lipid peroxidation ability of S. sarmentosum were the highest under suitable moisure + spraying H₂O₂ treatment, followed by drought + spraying H₂O₂ treatment. Conclusion Foliar spraying 1 mmol/L H₂O₂ could alleviate the oxidative damage of drought stress on S. sarmentosum, maintain mitochondrial homeostasis, and improve the yield and quality of S. sarmentosum, thereby coordinating the contradiction between yield and quality of S. sarmentosum under drought stress. Spraying H₂O₂ under suitable moisture conditions can also help to improve the yield and quality of S. sarmentosum.