Effects Of Environmental Factors On The Growth And Principal Medicinal Compositions Of Ginkgo Biloba Seedlings

This dissertation presented the study on the growth and main medicinal compositions of Ginkgo seedlings of two years under drought stress, light intensity and light quality, and the annual dynamic variations of the total flavonoids, terpene lactones in leaves, roots and stems from April to November. Meanwhile, the study also determined PAL activity of the key enzyme in secondary metabolism in leaves and analyzed the expression of 14 key enzyme genes in the metabolistic process of flavonoids, terpene lactones by RT-PCR. Then, it discessed the process of adaptation to the enviornment and its molecular mechanism from the perspectives of products, protein and nucleic acid of Gingko biloba. The main results were showed as following:1. Drought stress inhibited the growth of Ginkgo seedlings. It exerted greater influence on the metabolism of flavonoids, terpene lactones in leaves than their contents in stems and roots. Contents of flavonoids and terpene lactones in leaves were correlated significantly with drought stress. The content variation of flavonoids and terpene lactones in leaves displayed a double peaks curve and PAL activity and flavonoids content shared a similar changing pattern. Flavonoids reached its highest level in moderate drought. In the early stage of flavonoids metabolism, expressions of PAL, C4H and CHS genes corresponded with the ascending content of flavonoids, and those of F3H,FLS,ANS,ANR genes in later stage of flavonoid metabolism were entirely the same as changes of flavonoid content. Light drought helped in the accumulation of terpene lactones in leaves and roots. In the metabolism of terpene lactones through MVA , genes HMGR and MVD jointly regulated the metabolism of bilobalide, while genes DXS, DXR, MECT and MECPs in the metabolism of terpene lactones through MEP controled synthesis of diterpene lactones, and the experession of gene GGPPs corresponded with the content of total terpene .2. Light shade facilitated the growth of Ginkgo biloba. The variation of flavonoids and terpene lactones in the leaves showed a single-peak curve, and PAL activity and flavonoids content in the leaves didn't correspond to each other under different light intensity. In light shade treatment, flavonoids reached its peak in content, in whose later stage of metabolism, genetic expression and flavonoids mebabolism remained close relationship; Severe shade faciliated the accumulation of terpene lactones in leaves, in the metabolistic channel of which the genetic expression of MVA was entirely corresponding with the variation of bilobalide content, while in the metabolistic channel of MEP the expression of genes MECT and MECPs basically agreed with the variation of diterpene lactones content, and the experession of gene GGPPs in later matabolistic stage varied with the metabolism of total terpene lactones.3. Red light helped in the growth of aboveground parts, while blue light the growth of underground parts. The variation of flavonoids content and terpene lactones displayed a double-peak curve, and PAL activity didn't correspond with the variation of flavonoids content in the leaves. Red light was in favor of the flavonoids accumulation and the genetic expression of the key enzyme of later stage of flavonoids metabolism was basically in accordance with the variation of flavonoid contents. Blue light was favorable to the accumulation of terpene lactones in leaves and roots. The genetic expression of the key enzyme in the metabolism of MVA in terpene lactones was not in accordance with the variation of bilobalide contents but that of the key genes in MEP metabolism and GGPPs conformed with the content variation of terpene lactones in total.