Effects Of Different Stress On The Accumulation Of Tartary Buckwheat Flavonoids And Its Biosynthesis-related Gene Expression Profiles At Different Growth Stages

Tartary buckwheat (Fagopyrum tataricum) belongs to Polygonaceae, dicotyledonous plant. It is not only nutritious, but rich in flavonoids. It can be used as medicine and food plants. The major flavonoids of Tartary buckwheat are rutin, including flavonols, flavones, chalcones, flavanones and anthocyanins. Research shows that these compounds have variety of pharmacological activities, such as antioxidant, anticancer and etc. Because of the buckwheat flavonoid biosynthetic pathway is extremely complex, and the technical process principle of the studies from adversity stress is rarely reported.Therefore, the study throughout different organs (roots, stems, leaves, flowers and seeds)of Tartary buckwheat at the growing period(sprouting stage, seedling stage, flowering stage and maturity stage) have investigated the total flavonoids content alteration in different adversities stresses (Salt, Drought and UV-B), especially, relationship of total flavonoids content of flowering buckwheat and flavonoids synthesis-related gene expression, and key genes have affected on buckwheat total flavonoids content were studied systematically and so on. The main results are as follows:1. Using supersonic wave extracted concentration of total flavonoids of tartary buckwheat organizations in different growth stages (sprouting stage, seedling stage, flowering stage and maturity stage) determining concentration of total flavonoids with AICl3 method. The results showed that under different stress (100 mM NaCl,30% PEG-6000 and 0.1 mW/cm2 UV-B) treatments, total flavonoids content of buckwheat organs at different growth stages is not same. Under drought stress treatment, total flavonoids content of the flowers and leaves of flowering buckwheat stage was the highest. After 12 h, total flavonoids content of flowers reached a peak, and increased 5.27% compared with the control group. After 24 h, total flavonoids content of leaves reached a maximum, compared to the control group, and increased 9.81%. Under salt stress, total flavonoids content of flowers and leaves of flowering buckwheat was secondly highest. After 12 h treatment, total flavonoids content of flowers and leaves reached a maximum, compared to the control group, increased 4.5%,9.6%, respectively. Under UV-B stress treatment, total flavonoids content of leaves at flowering buckwheat stage increased at least. After 24 h, total flavonoids content of leaves reaches a maximum, and increased 3.33%, compared to the control group. While total flavonoids content of flowers declines, after 24 h reaches a minimum, compared to the control group, and decreased 3.33%. Under different stress treatments, flavonoids content of roots and stems of buckwheat in the bud stage, seedling stage and mature remained at about 1.5% and 2.4%, mature seeds remained at around 2.6%, bud stage and seedling leaf total flavonoids content significantly (P<0.05) increased, while maturity is diametrically opposite. In short, different stress treatments at different growth stages of buckwheat showed total flavonoids content of leaves is the highest, various organs’flavonoids content of flowering stage of buckwheat are is basically higher than other stages.2. Using flowering buckwheat under NaCl, PEG and UV-B stress treatment as materials. Through Real-Time PCR and H3 gene as reference gene, detection of different tissues flavonoid biosynthesis genes FtPAL, FtC4H, Ft4CL, FtCHS, FtCHI, FtF3H, FtF3’H, FtFLSl and FtFLS buckwheat flowering in roots, stems, leaves, flowers showed differential expression:After by different stress treatments FtPAL, FtC4H, Ft4CL, FtCHS, FtCHI, FtF3H, FtF3’H, FtFLSl and FtFLS were expressed in stems, leaves, flowers; FtPAL, FtC4H, Ft4CL, FtCHI, FtF3H, FtF3’H, FtFLSl and FtFLS were expressed in roots, and almost undetectable expression of FtCHS. Statistical analysis showed that under NaCl stress conditions, FtCHS was in roots and stems, expression differences of FtFLS1 in the control group stems was not significant (P>0.05); under PEG stress, FtCHS and FtFLS in roots, FtFLS in stem the expression of the control group had no significant difference in (P>0.05); under UV-B stress, FtCHS and FtFLS in roots, FtC4H, Ft4CL, FtCHS, FtCHI, FtF3 H, FtFLS expression level of control in the stem group difference was not significant (P>0.05); other genes under different stress conditions, and its expression are at a significant level (P<0.05). The results showed that the expression of different genes and tissue had a specific expression patterns under different stress conditions. Different stress conditions can up-regulate the expression of FtPAL, FtC4H, Ft4CL, FtCHS, FtFLSl in flowers and FtPAL, FtCHS, FtFLSl in leaves; the expression of FtPAL, FtC4H, Ft4CL, FtCHI, FtF3H, FtF3’H and FtFLS in roots and stems was down-regulated.3. By analyzing the relationships among total flavonoids content and expression level of genes under different stress treatments, we speculated that:under different stresses, Buckwheat roots and stems may regulate the synthesis of flavonoids by FtCHS and FtFLSl coordinated expression. In buckwheat leaves and flowers, FtPAL, FtCHS, FtFLS1 and FtPAL, FtC4H, Ft4CL, FtCHS, FtFLS1 respectively co-regulate the synthesis of flavonoids。4. Through the study on different adversities (salt, drought, UV-B) of the different variations growing buckwheat total flavonoids, and relationship between flowering buckwheat flavonoids content and flavonoids synthesis-related genes is to enhance high resistance and nurture high flavonoids content features of buckwheat provide a theoretical basis and practical guidance.