| In order to understand the effects of environmental factors on biosynthesis and accumulation of metabolites（flavonoid and terpene lactone） in ginkgo（Ginkgo biloba L.） leaves, we designed a two factors experiment in phytotron. 2-year old ginkgo seedlings were planted in pot using soil. The experiment included two environmental factors of temperature（T） and light intensity（Q）, and every environmental factor had three levels. The total treatments were nine, including T1Q1(15℃/5℃,300μmol.m-2.s-1),T1Q2(15℃/5℃,500μmol.m-2.s-1), T1Q3(15℃/5℃,800μmol.m-2.s-1),T2Q1(25℃/15℃,300μmol.m-2.s-1),T2Q2(25℃/15℃,500μmol.m-2.s-1), T2Q3(25℃/15℃,800μmol.m-2.s-1),T3Q1(35℃/25℃,300μmol.m-2.s-1),T3Q2(35℃/25℃,500μmo l.m-2.s-1)and T3Q3(35℃/25℃,800μmol.m-2.s-1), and the treatment time was 40 days. The indexes of growth, soluble sugar and protein content, flavonoid and terpene lactone content, hormone, activity and gene expression of biosynthesis enzymes were determined in 10 d, 20 d, 30 d and 40 d after treatment, and the relations between secondary metabolites and growth, primary metabolites, hormone, enzyme activity and enzyme gene expression were analyzed. The main results were as follows:1. Temperature and light intensity affected height, ground diameter, biomass and biomass distribution significantly. The condition of T2Q1 was most beneficial to the growth of height, ground diameter and biomass, while T1Q3 treatment was favorable to the accumulation of leaf biomass.2. Temperature and light intensity affected the content and composition of flavonoid and terpene lactone in ginkgo leaves significantly, and also affected flavonoid and terpene lactone yield per seedling remarkably. Lower temperature and higher light intensity were beneficial to the accumulation of flavonoid in ginkgo leaves, while higher temperature and higher light intensity were in favour of the accumulation of terpene lactone. 40 d after treatment, T1Q3 had highest flavonoid yield per seedling, but T3Q3 had highest terpene lactone yield per seedling.3. The hormone contents of ABA, IAA, GA and ZRwere affected by temperature and light intensity significantly. Higher temperature limited the biosynthesis of IAA, GA and ZR, but increased ABA content in ginkgo leaves. The changing tendency of flavonoid content was reverse with that of IAA and ZR contents, and also the terpene lactone content with IAA, GA and ZA contents.4. Temperature and light intensity affected the content of soluble sugar and protein, and the activity of PAL, C4 H and 4CL in ginkgo leaves significantly. Lower temperature and higher light intensity were beneficial to the accumulation of soluble sugar, while higher temperature and higher light intensity were favorable to the accumulation of soluble protein. There was a positive correlation between soluble sugar and flavonoid content, while it was a negative correlation between soluble sugar and terpene lactone content. The protein content had a negative correlation with flavonoid and terpene lactone content.5. The activity of PAL, C4 H and 4CL could promoted by lower temperature and higher light temperature in short time, but they were inhibited with increasing of treatment time. The activity of PAL, C4 H and 4CL had a negative correlation, middle positive correlation and weak positive correlation with flavonoid content separately.6. The gene expression of flavonoid and terpene lactone biosynthesis enzymes was affected by temperature and light intensity significantly. Lower temperature and higher light intensity were helpful to the gene expression of C4 H and FLS, while higher temperature and light intensity were favorable to the gene expression of CHS, ANS, MVD and MECT, but higher temperature and lower light intensity were beneficial to the gene expression of ANR, HMGR and DXS.7. There was no strong correlation between gene expression of enzymes and metabolite（flavonoid and terpene lactone content）. Most of them showed weak and middle correlation, suggesting that the accumulation of metabolites was not only decided by biosynthesis enzymes.In conclusion, the biosynthesis and accumulation of flavonoid and terpene lactone were not decided by single factor, and it depended synthetic action of multi-factor, such as hormone, enzyme activity, primary metabolite and gene expression of biosynthesis enzyme. |
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