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研究了外源油菜素内酯(24–表油菜素内酯,EBL)对Ca(NO_3)_2胁迫下黄瓜光合器官的调控作用。在Ca(NO_3)_2胁迫条件下,外源EBL显著提高了叶绿体中还原型抗坏血酸和谷胱甘肽的含量,分别是对照的2.44倍和1.40倍。AsA-GSH循环中的抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性比胁迫处理增加了36.27%和105.83%。外源EBL的施用显著增加了紫黄质(V)、玉米黄质(Z)和总叶黄素含量,减少了花药黄质(A)的积累,叶黄素脱环氧化态比胁迫处理增加了9.60%。胁迫条件下,EBL显著提高了植株叶片的非光化学猝灭(NPQ),缓解了PSⅡ实际光化学效率(Φ_(PSⅡ))的下降。EBL处理后,叶绿体膜多种不饱和脂肪酸的水平比对照明显增加。试验结果表明,外源EBL能够通过调控AsA-GSH循环及热耗散,增强叶绿体抗氧化能力,从而抵抗Ca(NO_3)_2胁迫。
The effects of exogenous brassinosteroids (24-epibrassinolide, EBL) on the photosynthetic organs of cucumber under Ca (NO 3) 2 stress were studied. Exogenous EBL significantly increased the levels of ascorbic acid and glutathione in the chloroplasts under Ca (NO_3) _2 stress, which were 2.44 and 1.40 times of the control, respectively. The activities of ascorbate peroxidase (APX) and glutathione reductase (GR) in AsA-GSH cycle increased by 36.27% and 105.83% compared with the stress treatment. Administration of exogenous EBL significantly increased the content of violaxanthin (V), zeaxanthin (Z) and total lutein, decreased the accumulation of anther lutein (A), and the lutein de-epoxidation state An increase of 9.60%. Under the stress conditions, EBL significantly increased the non-photochemical quenching (NPQ) of plant leaves and alleviated the decrease of the actual photochemical efficiency (Φ PSII). EBL treatment, chloroplast membrane polyunsaturated fatty acids levels significantly increased compared with the control. The results showed that exogenous EBL could resist Ca (NO_3) _2 stress by regulating AsA-GSH cycle and heat dissipation, enhancing the antioxidant capacity of chloroplasts.