Effects And Mechanism Of Hydrogen-Rich Water(HRW) On The Hypocotyl Elongation And Isoflavones Biosynthesis Of Soybean Sprouts Under UV-B Irradiation

In recent years, with the industrial production of sprouts and consumers'strict requirements for food safety, it has become the new research focus in protected cultivation that plant lighting were utilized as a source of to improve the growth and quality of sprouts in vegetable cultivation. In this study, 'Dongnong690' soybean was tested to investigate the influence of hydrogen rich water of the length of soybean hypocotyl, the oxidation resistance and the synthesisof soy-isoflavones. The main results were as follows:1.The sprouts hypocotyl elongation had significant differences under the conditions of the dark and UV-B radiation.The hypocotyl length under the dark significantly longer than UV-B. HRW promoted the hypocotyl elongation under the dark, but inhibits the hypocotyl elongation under UV-B radiation. In the case of light environment remains the same,darkrs and UV-B"s hypocotyl elongation contrary trend of elongation,after adding hydrogen rich water (HRW).Under the dark state,HRW didn't improve the activity of antioxidant enzymes.When there is the UV-B stress of sprouts,HRW significantly increase the enzyme activity, adumbrative HRW has great potential in adversity stress resistance.2.UV-B radiation promoted the enzyme activity of Phenylalanine ammonia enzyme (PAL). PAL enzymes are the first enzyme in the metabolic pathway of benzene propane class,which is the key enzyme and speed limit enzyme.The enzyme activity of a direct impact on the synthesis of phenolic substances in plants.UV-B radiation promotes the improvement of the PAL enzyme activity, so the total phenol content also increase accordingly.When the UV-B together with HRW,PAL enzyme activity than UV-B radiation treatment alone had more obvious improvement, total phenol content also increases. This is because the addition of HRW improved the PAL enzyme gene expression, thus increase the PAL enzyme synthesis.3.HRW can strongly suppress Glycitein biosynthesis and promote the synthesis of Daidzein,but there is an part of the same biosynthetic pathway between them.So we speculated that HRW in the synthesis way of soy isoflavones play a regulatory role to promote the soybean isoflavone precursor synthesis in the direction of Daidzein,thus reducing the synthesis of Glycitein.4.Under the UV-B radiation and HRW,the sprout's UVR8 gene expression quantity rising sharply within 48 h.But after 72 h and 96 h,UVR8 expression quantity back to control rate, illustrate the HRW under UV-B radiation can promote the expression of UVR8 sharply.UV-B radiation alone,there are no make UVR8 increased expression,but increased in the treatment of phenol content,shows that UV-B radiation promote UVR8 dimer dissociation,to participate in the signal transduction of UV-B,so as to promote the synthesis of phenolics.