Related Mechanisms Research On Ultraiolet A Light Inducing The Anthocyanins Synthesis In The Hypocotyls Of Soybean Sprouts

In recent yeas,with the use of light control technology in the production of sprouts and the increased requirements for food safety,it has become the new research hotspot to improve the growth and quality of sprouts via the technology of light environment control in vegetable cultivation.In this study,'Dongnong 690' soybean sprouts were tested to investigate relative molecular mechanism of UV-A induced anthocyanin synthesis in the hypocotyls of soybean sprouts,and different shading treatment on the synthesis of anthocyanins.Our research will improve nutritional value of soybean sprouts and make positive contribution for application of UV-A irradiation in theindustrial production of soybean sprouts.The main results were described as follows:1.Soybean sprouts grown in the dark showed yellow cotyledons while sprouts grown under white(W),blue(B)and UV-A lights showed green cotyledons.The anthocyanin content in the hypocotyls of soybean sprouts was low at 0 h,about 2 U·g-1FW.Compared with the dark and other light quality cultivations,UV-A treatment significantly improved the content of anthocyanin in the hypocotyls of soybean sprouts.As the illumination time goes on,anthocyanin accumulation was increased gradually.The content of anthocyanin reached a maximum of 43 U·g-1 FW at 36 h under UV-A,which was significantly higher than those in the other treatments.The activities of PAL and CHI were higher at 0 h.Compared to that in the dark and other light treatments,continuous UV-A light treatment for 24 h and 36 h significantly increased the activity of phenylalanine ammonia-lyase(PAL).Continuous UV-A light treatment for 12 h and 24 h significantly increased the activity of and flavonoid glycosyltransferase(UFGT).There was no difference in the expression of anthocyanin related genes among different treatments at 0 h.Continuous UV-A treatment for 36 h significantly up-regulated the expression of regulator gene MYB75 and light receptor genes(CRY1,CRY2 and UVR8)to about 12-,30-,6-and 2-fold,in the hypocotyls of soybean sprouts compared with those in the other treatments,respectively.Moreover,continuous UV-A treatment for 12 h significantly up-regulated the expression of anthocyanin biosynthesis-related structural genes(PAL,CHS,DFR,ANS,UFGT)to about 58,10,6,44 and 47 times,respectively.In Conclusion,UV-A induced anthocyanin accumulation by improving the activity of PAL and UFGT and up regulating the expression of related genes in the hypocotyls of soybean sprouts.2.Different shading treatments(covering the cotyledon,the upper part of hypocotyls or the lower part of hypocotyls)all decreased anthocyanins content significantly in the hypocotyls with UV-A irradiation.Accordingly,the expression of DFR?ANS and UFGT in shading sites were down-regulated and PAL activity deceased abviously.UV-A-induced anthocyanins mainly biosynthese locally in the lower section of hypocotyls in soybean sprouts,but not systematically synthetise.Cotyledon shading treatment had a limitation on anthocyanin biosynthesis by down-regulating the expression of anthocyanin biosynthesis-related genes.