The Research On The Mechanism Of UV-B-mediated Transcription Factor HY5 Regulating The Anthocyanin Synthesis In Zanthoxylum Bungeanum

Zanthoxylum bungeanum is not only a traditional economic tree,but also can be used as fruit viewing,hedgerow and aromatic trees in gardens.The fruit color is an important feature for Z.bungeanum,and the accumulation of anthocyanin is the main reason for the redness of the fruit.The formation of anthocyanin in plants depends on light signals.Researches have found that the bZIP transcription factor HY5 is the most critical and representative transcription factor in plant photomorphogenesis.In this study,ZbHY5 in Z.bungeanum was screened and identified based on the transcriptome,and the molecular mechanism of its regulation of UV-B-mediated anthocyanin synthesis was clarified.The main findings are as follows:(1)In the natural growth condition,the fruit of Z.bungeanum would gradually change from green to red.Through bioinformatics analysis of the transcriptome data of Z.bungeanum fruit in four growth periods,a transcription factor gene ZbHY5 related to the anthocyanin synthesis was screened out.(2)The Z.bungeanum fruit was bagged in the field.We found that bagging would keep the fruit green all the time,and the fruit would gradually turn red after unbagging.Quantitative determination found that both the expression level of ZbHY5 and the content of anthocyanin increased significantly.(3)The leaves of Z.bungeanum in the natural growth state were always green.After UV-B radiation,the leaves gradually changed from green to red,and the expression level of ZbHY5 and the content of anthocyanin increased.(4)The CDs region of ZbHY5 was cloned,and the function of ZbHY5 was verified by transient gene overexpression assay.It was found that the overexpression of ZbHY5 deepened the red color of Z.bungeanum leaves,promoted the expression level of ZbHY5 and ZbMYB113 and the accumulation of anthocyanin.(5)The CDs region of ZbMYB113 was cloned,and the interaction between ZbHY5 and ZbMYB113 was proved by bimolecular fluorescence complementation(BIFC)assay.In conclusion,these results showed that ZbHY5 was involved in the UV-B-mediated anthocyanin synthesis and accumulation in Zanthoxylum bungeanum,and this process was probably achieved through the interaction between ZbHY5 and ZbMYB113.This study will provide the basis for further research on the UV-B-induced anthocyanin accumulation in Z.bungeanum.