Studies On Characteristic And Physiological Mechanism Of Sugar Accumulation In Myrica Rubra Seib.et Zucc. Fruit

Waxberry(Myrica rubra Seib. et Zucc.) which is one of speciality fruit in china has been rapidly developed as one of important fruit in southern china in recent years. On account of its fruit quality forming and regulation physiological mechanism not been known, people could not take a pertinence technology to improve quality. So there were some problems in market, such as low ratio of high quality fruit, small fruit and bad flavor. Fruit quality always was regarded as study focus, including appearance and inherence. Sugar content in fruit was a dominant factor to evaluate fruit quality. It was not only relation to flavor, as foundation material to synthesize carotenoid, pigment and fragrance and participated metabolism, but also played a role of signal molecule in cell signaling. So study of sugar accumulation characteristic and physiological mechanism in fruit was a important and foundational research task about improving fruit quality. With materials of Dongkui, Biqizhong and Shuimei, the experiment knowed about sugar accumulation rule by measured sugar content in different development stages fruit with HPLC, and elucidated regulation role of sucrose metabolizing enzymes by study of theirs activity change, then studied correlations among sugar accumulation, coloring regulation, changes of acid and pH. Finally, the experiment discussed effects of removal fruit and defoliation for sugar metabolism and accumulation, so as to provide theory basis for high quality culture. The major results can be summarized as below: 1. Sugar composition in waxberry fruit mostly were sucrose, fructose and glucose. Thereinto, mostly sugar was accumulated with sucrose form. Fructose and glucose only accounted for one fourth of total sugar. Sucrose concentration was low during fruit development early and middle days and rapidly accumulated during from 52 days after full bloom(DAF) to maturity. Glucose and fructose concentration that approximately kept consistency with sucrose accumulation were higher at 1st stage(at the front of 32 DAF), the lowest 2st stage(32-63 DAF) and rapidly accumulated to the highest at 3st stage(after 63 DAF). 2. The changes of sucrose metabolizing enzymes activity. There was so higher hydrolyze enzymes activity at 1st stage during waxberry fruit development that sucrose was analyzed to supply energy source for metabolism and cell division. Ivr, SPS and SS activities dropped at slow growth. After 52 DAF, Ivr activity was slightly increased but still lower, SPS activity increased, and SS+ maintained lower activity. Furthermore, SS- activity was sill higher. So sucrose was analyzed so as to keep higher concentration grads to accumulate sucrose by symplastic phloem unloading pathway. After fruit turned red, the proportion of photosynthesis product analyzed decreased on account that fruit expanded slowly and SS- hydrolyze activity reduced, so sucrose content was accumulated rapidly. At front of fruit maturity 10 days, hexose content was not increased and sucrose concentration was already higher but was still rapidly accumulated, so we could conclude that transportation depended on initiative apoplasmic phloem unloading pathway at some time. 3. Waxberry fruit sugar accumulation was correlated with coloring and change of acid and pH. The content of chlorophyll and carotenoid dropped from the highest to the lowest during fruit development and negatively correlate with sugar accumulation. At 3st stage, fruit-color began to turn red during sugar accumulation because of anthocyanin accumulation. The change of anthocyanin content was distinct correlation with sucrose and hexose accumulation. So they possibly synthesized anthocyanin as former substance. The dropping process of aid was reverse with sugar accumulation and was distinct correlation with sucrose and hexose accumulation. When fruit ripened, the content of acid was under 1% and pH maintained between 3.3 and 3.4. So content of acid was so low that could not largely hydrolyze sucrose but in favor of stability of anthocyanin. 4. The study of regulation between s...