Study On Phloem Unloading Pathway Of Photosynthates And Rules Of Anthocyanin Synthesis Accumulation Of Blueberry

The blueberry (Vaccinium ssp.) fruit is rich in polyphenols, especially the flavonoids, and the high health care value of blueberry is more and more favored by the world. Now, at home and abroad the studies about blueberry are mainly concentrated in the field of cultivation techniques、 excellent breed selection、pest control and prevention、medical efficacy and biological sciences,etc. But the research of phloem unloading path of blueberry fruit is still blank. The Highbush blueberry(Vaccinium corymbosum) ’Sunrise’ and ’Sierra’ fruits were selected as the test materials. The ultrastructures of phloem and its surrounding parenchyma cells were systematically observed by transmission electron microscopy. The unloading pathway of assimilate in blueberry fruit was systematically investigated by confocal laser scanning microscopy and fluorescent dye tracer technology. The contents of anthocyanin、five endogenous hormone(ABA, IAA, ETH, ABA, ZT)、soluble sugar and their related metabolic enzyme activity, and their correlation by using high performance liquid chromatography (HPLC) and other technologies. The aim of this study is to provide theoretical basis for the blueberry fruit development and quality formation. The results indicated that:1:The study of phloem photosynthate unloading path.Structural investigations and the CF imaging showed that there was no plasmodesmata between the sieve element companion cell (SE/CC) complex and its surrouding phloem parenchyma cells during the whole developmental process of fruit, resulted in the symplastic isolation between them. There were lots of plasmodesmata among the phloem parenchyma cells. Carboxy fluorescein(CF) was restricted to the phloem. The above results showed that the apoplastic unloading may be the main pathway of the phloem unloading in blueberry fruit at the whole developmental stage,and the unloading pathway was not changed. There was no difference between the two blueberry varieties.2:The research of sugar content and its related metabolic enzyme activity in blueberry.The fruit of two blueberry cultivars were mainly accumulated hexoses (fructose and glucose). During the fruit developoment, the invertase, sucrose synthase and sucrose phosphate synthase enzyme controled the accumulation and synthesis metabolism of surcrose together. During the whole development process of blueberry fruit, the change of sugar content and its related metabolic enzyme activity did not exist significant turning points, which was consistent with the phloem photosynthate unloading paths, so it showed that the suger metabolism had a closely relationship with assimilation unloading.3:The research of the synthesis and accumulation rules of anthocyanin.The synthesis of sugar provided the material basis for the accumulation of anthocyanin, all factors promoting sugar accumulation can promote the synthesis of anthocyanin. The enzymes related sucrose metabolism(SS, SPS, SAI, CWI, NI) can corordinated control the the sugar accumulation,which can provide sufficient precursor substances for the synthesis of anthocyanin,so the enzymes can promote the synthesis of anthocyanin.ABA, IAA, GA3 and ETH can coordinated control the sugar accumulation and the synthesis of anthocyanin, ABA and ETH were the important inducing factor for sugars,they can promote the accumulation and synthesis of anthocyanin, IAA can restrain the accumulation of sugars, so at the same time, it can restrain the accumulation and synthesis of anthocyanin.But the regulation function of GA3 was not obvious.