马铃薯抗坏血酸含量及其代谢相关酶活性关系的研究

Relationship Between Ascorbic Acid Content and the Enzyme Activities Involved in AsA Metabolism of Potato

为探讨马铃薯不同器官中抗坏血酸(AsA)含量及其代谢相关酶活性关系,研究了马铃薯幼叶、功能叶、老叶、茎和块茎中AsA和其氧化态脱氢抗坏血酸(DHA)的含量与L-半乳糖-1,4-内酯脱氢酶(GalLDH)、脱氢抗坏血酸还原酶(DHAR)、谷胱甘肽还原酶(GR)、抗坏血酸过氧化物酶(APX)、抗坏血酸氧化酶(AO)和单脱氢抗坏血酸还原酶(MDHAR)等6种酶活性之间的相关性。结果表明,马铃薯AsA在幼叶和块茎中含量很高。叶片和茎的抗坏血酸库(AsA与DHA之和)水平与GalLDH活性显著相关,而AsA含量与DHAR活性显著相关,DHA含量与APX活性显著相关。说明在马铃薯幼叶中高含量的AsA可能由于GalLDH和DHAR的高活性;而块茎中AsA的积累,主要来自于叶片的运输和DHAR催化的DHA再生。

To investigate the relationship between ascorbate （AsA） distribution and the activities of enzymes involved in AsA metabolism, the AsA and dehydroascorbate （DHA） contents and the activities of six related enzymes were studied in various organs of potato, i.e. young leaves, mature leaves, aged leaves, stems and tubers. The results showed that AsA was accumulated in young leaves and tubers. AsA pool size （the sum of AsA and DHA） in leaves and stems was correlated with L-galactono-1, 4-1actone dehydrogenase （GalLDH） activity. AsA content was significantly related with the dehydroascorbate reductase （DHAR） activity in all organs, especially in tubers. Meanwhile, DHA content was significantly associated with ascorbate peroxidase （APX） activity. This suggested that high AsA content in young leaves might result from higher activites of GalLDH and DHAR, while AsA accumulation in tuber might be attributed to the transportation from leaves, and DHA recycling via DHAR.