Studies On The Physiological Property Of L-Ascorbic Acid Accumulation Of Rosa Roxburghii Tratt

Rosa roxburghii Tratt is a kind of newly emerging fruit tree which originnated and distributes in China and has extremely high content of AsA .Heretofore ,the study of it's physiology, especially the physiogical property of AsA accumulation was far from deep-going .So, Rosa roxburghii Tratt cv. 'Guinong5' was used to investigate changes in Ascorbic Acid(AsA) and sugar levels together with activities of L-galacttono-l,4-Lactone dehydrogenase (GalLDH, a key enzyme in AsA biosynthesis in higher plant), AAO,APX,MDAR and DHAR in fruits and leaves during development in order to clarify the physiogical property of AsA accumulation of the plant that has extremely high content of AsA and results showed as follows:AsA accumulated continually but with a slow, fast and slow accumulating rate in the R . roxburghii fruits during its development, in which the period from the end of June to the early of August was the most important period of AsA accumulation . Changes of AsA content coincided with fruit development. The extremely significant positive correlation exised between the GalLDH activity and AsA accumulating rate (r~2=0.630**). Transitory and low activities of AAO and APX (AAO or APX , a enzyme catalyzes the reduced of As A to mondenydroasorbate ) in fruits were detected in the initial stage of development . Furthermore no activity of MDAR or DHAR in the fruit was detected during the whole development. The positive correlation exsited between the AsA accumulating rate and content of glucose and frucose ( glucose or frucose , the substrare can indirectly converse AsA in L-galatose pathway in higher plant),but no content of GAL ( L-galactono-l,4-lactone , the substrare can directly converse AsA in L-galatose pathway in higher plant) in fruits was detected during the whole development.The changes of the content of the reduced AsA and total AsA in leaves of R . roxburghii expressed as a low, high and low pattern capitally during development, with a peak at the stage of July and June respectively . The significant positive correlation existed between the GalLDH activity and total AsA content (r~2=0.694**). No activity of AAO,APX,MDAR or DHAR in leaves was detected during the whole development. A positive correlation was found between reducting sugar content and the reduced AsA content; however ,a significant positive correlation exsited between total soluble sugar content and the reduced AsA content in leaves .Diurnal changes of AsA accumulation in fruits of R . roxburghii expressed as anegatively fast, positively fast , positively slow and positively fast regime with themost important period of AsA accumulation from 13:00 to 19:00. The positivecorrelation exised between the GalLDH activity and AsA accumulating rate (r~2=0.459*) . The relatively high activity of APX in fruit was detected from 7:00 to 16:00;...