Study On Flavonoids Metabolism And Its Defensive Mechanism In Buckwheat Under UV Stress

Flavonoids is one of the main types secondary metabolites in plants. UV stress usually causes the enhancement of metabolism of flavonoids, which can function as UV-filter in plant. The new cultivar 9279-21 of buckwheat(Fagopyrum tataricum L). was used as material to investigate the adaptive mechanism of flavonoids metabolism under UV stress.1. Response of flavonoids secondary metabolism to UV stress.Buckwheat flavonoids was analyzed through HPLC method. The result showed that the seedling of buckwheat contained puerarin, naringenin, quercetin, rutin, luteolin and kaempferol, and the three main components are quercetin, rutin and raringenin. The treatment of UV stress increased the content of flavonoids significantly, decreased the height of seedlings, diameter of leaves and the dry matter. The supply of rutin could reduce the growth of buckwheat seedlings to a certain degree.The activity of PAL and DAHPS in shikimate-phenylpropanoids metabolism pathway was also enhanced by UV stress, leading the acceleration of shikimate-phenylpropanoids metabolism pathway and the content increase of secondary metabolism matter flavonoids. And the increase of PAL and DAHPS activity caused increasing of G6PDH activity, which further benefit the shikimate-phenylpropanoids metabolism pathway and promoted the formation of flaviloinds. This is the important reason for the short term significant increase of the flavonoids in plants under UV stress.2. The relationship between flavonoids metabolism and the adjustment of respiration, carbon and nitrogen metabolism as well as hormone metabolism under UV stress.The experiment of respiration inhibitor showed that the PPP pathway was enhanced under UV stress. The proportion of PPP pathway was elevated by UV stress through the improvement of the key enzyme G6PDH activity in the PPP pathway. The E4P produced in PPP pathway was conversed into shikimate and entered the shikimate pathway, which is good...