Kanokporn Sompornpailin

Increasing Plant Flavonoid Biomaterials in Response to UV-A Light

Flavonoid biomaterials have a protecting function from various stresses. We examined the flavonoid biosynthesis in plant treated under visible light (VL) and additional UV-A light. The transgenic tobacco containing PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1) cDNA, involved in flavonoid biosynthesis from Arabidopsis thaliana, were used for studying the flavonoid biosynthesis under both light conditions comparing to non transgenic tobacco. The flavonoid biomaterials were extracted with acidic methanol and water solvent from treated plant leaves. The absorbance of each biomaterial in the extract was measured under specific wavelength using a spectrophotometer. Additional UV-A radiated to non transgenic and transgenic tobacco affect the increasing of p-coumaric acid, naringenin, apigenin and kaempherol biomaterials from themselves grown under VL (approximately 120-130%). However, PAP1 transgenic tobaccos under additional UV-A radiation enhance the accumulation of these biomaterials up to160-180% higher than non transgenic tobaccos grown under VL condition. Moreover, PAP1 transgenic tobacco radiated with UVA light also significantly increased pelargonidin biomaterial. PAP1 transgenic tobaccos had a similar phenotype with non transgenic tobaccos but the color of fully expanding flower was more pink intensity than non transgenic.

Antioxidant Activities of Transgenic Flower Over-Expressing FLS and TT8 Involving in Flavonoid Biosynthesis

Transgenic differently over-expressed cDNA involving in flavonoid biosynthesis (FLAVONOL SYNTHASE: FLS and TRANSPARENT TESTA 8: TT8) and wild type plants were grown in the culturing room radiated with fluorescent light. Flowers of each transgenic and WT were collected and extracted with acidic methanol. The flower extracts were analyzed for the relative content of each flavonoid subgroup by spectrophotometry. The result showed that the both transgenic extracts contained flavanone and flavone higher than WT extract did. The FLS extract contained the highest amount of flavonol content (1.4 times) following with the TT8 extracts (1.25 times) comparing to WT extract. The TT8 extract has anthocyanin content approximately 3 times, while the FLS extract has only 0.5 times of WT. The extract was used to evaluate the antioxidant capacity by ABTS and DPPH methods. The result showed that, both transgenic extracts have a better antioxidant capacity than WT extract. Both transgenic extracts have similar results of EC50 performed by DPPH method, however the TT8 extracts showed the highest antioxidant capacity under ABTS experimental condition. Therefore, types and concentration of flavonoids in the extract could directly affect the antioxidant capacity.

Beneficial Effects of Zinc Oxide Nanoparticles on Plant Regeneration of Vetiver Grass (Vetiveria zizanioides L. Nash)

Zinc is an essential micronutrient element for plant. Nowadays, Zinc oxide nanoparticles (ZnO NPs) are widely used and have been shown adverse effects to plant physiology. The optimal concentration of ZnO NPs added in plant regeneration medium (PRM) is studied in this experiment. Six-weeks old calli induced from the aseptic axillary buds of vetiver grass were cultured in PRM with various concentrations of ZnO NPs (5, 10, 20, 40 mgL-1). PRM containing 5, 10 mgL-1 ZnO NPs showed the highest percentage of plant regeneration frequency (95%) but did not have a statistic difference with other treatments. However, the averages of shoot length regenerated under both concentrations were 1.32-1.33 cm. These averages of shoot length had statistically different from averages of shoot length of the others. Moreover, calli regenerated under PRM containing 5 mgL-1 ZnO NPs condition showed the highest average number of shoots per callus (9.75 shoots) with a statistic difference. ZnO NPs at 20-40 mgL-1 in the PRM did not enhance the percentage of plant regeneration, but retarded calli development and shoot elongation. The optimal concentration of ZnO NPs in PRM has positive effects on regeneration and development of vetiver grass under tissue culture condition.

Antioxidant Activity in the Petal Extract of PAP1 Transgenic Tobacco

Flavonoids are compounds which act as antioxidants in both plant and human. These substances are found in reproductive tissues. Tobaccos expressing ORF of PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1) involved in flavonoid biosynthesis were used for investigating the flavonoid profiles and antioxidant activity of petals and compared to wild type (WT) tobacco. Approximately two months, the tobacco grown in a culturing room had produced flowers for harvesting. The petal tissues were extracted with the solvent of acidic methanol and water. These extracts were measured the specific wavelength of flavonoid derivatives by using a spectrophotometer. The petal extract of H7 line showed the highest content of all detected flavonoid subgroups. However the petal extract of transgenic line H5 and H7 had significantly higher levels of anthocyanin (pelargonidin) than those of the other transgenic and WT tobaccos. An antioxidant activity of the petal extract was evaluated by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) assay. An effective concentration of the extract which scavenged DPPH radical by 50% (EC50) was presented. EC50 of the H5 and H7 transgenic extracts was approximately two folds less than that of WT extract Therefore anthocyanin may highly affect on antioxidant activities.