| 摘要: |
| 以苹果（Malus domestica Borkh）品种嘎拉（Gala）秋梢成熟叶片为试材，在水培养条件下，研究了离体苹果叶片衰老过程（0，6，12，18，30，48和72 h）中抗坏血酸-谷胱甘肽（ASA-GSH）循环及ASA合成关键酶L半乳糖-γ-内酯脱氢酶（GalLDH）的变化。结果表明，在整个衰老过程中，伴随H2O2含量、质膜相对透性和MDA含量升高，离体苹果叶片中单脱氢抗坏血酸还原酶（MDHAR）活性下降，抗坏血酸过氧化物酶（APX）和脱氢抗坏血酸还原酶（DAHR）活性分别在18和30 h达到最高值，而后开始下降。GalLDH对苹果叶片离体衰老反应迅速。在6 h活性达到最高，而后开始迅速下降。ASA/DHA，总ASA和总GSH含量随离体培养时间的延续均先上升而后下降，而GSH/GSSG比值在叶片离体衰老过程中一直下降。说明在苹果叶片离体衰老过程中，抗氧化剂ASA代谢主要是通过提高DHAR活性来维持其高水平，抵制衰老。 |
| 关键词: 苹果 离体叶片 抗坏血酸-谷胱甘肽循环 L-半乳糖-γ-内酯脱氢酶 |
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| 基金项目:西北农林科技大学“拔尖人才支持计划”；农业部948项目(2006-G28) |
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| Changes on ascorbate metabolism during senescence of detached apple leaves |
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| Abstract: |
| The changes of ascorbate-glutathione (ASA-GSH) cycle,ascorbate biosynthesis in the detached leaves of apple (Malus domestica Borkh cv.Gala) during leaves senescence （at 0，6，12，24，36，48 and 72 h after cultured with water） were investigated in this paper.The results showed,with increasing content of H2O2 and MDA and relative electric conductivity,the activity of monodehydroascorbate reductase (MDHAR) decreased,and the activities of ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) all decreased when they reached maximum at the 18th and 30th hour of senescence respectively.L-galactono-γ-lactone dehydrogenase (GalLDH) increased rapidly and the activity reached maximum at 6 h and then decreased.ASA/DHA,ASA pool and GSH pool all increased before 30 h and then decreased along with the senescence,and GSH/GSSG decreased obviously.These indicate that ASA,as a main antioxidant,is maintained and improved by increasing DHAR activity during senescence of apple leaves to imped senescence. |
| Key words: apple detached leaf ascorbate-glutathione cycle L-galactono-γ-lactone dehydrogenase |
