Genome-wide Investigation Of The MYB Transcription Factor Gene Family And Regulating Flavonoid Biosynthesis Genes In Zanthoxylum Bungeanum Maxim.

Zanthoxylum bungeanum Maxim.(ZBM)is an important economic crop in China.As one of the famous “eight condiments”,Z.bungeanum is a traditional spice and Chinese medicine.MYB transcription factors(TFs)have been suggested to play crucial roles in regulating the biosynthesis of flavonoids.However,there is no comprehensive analysis of MYB in Z.bungeanum.Therefore,in this study,we performed a comprehensive bioinformatics analysis of the MYB gene family in Z.bungeanum,in order to clarify the evolutionary mechanism of MYB gene family in detail.The phylogeny together with gene expression profiles analysis and correlation analysis predicted the function of MYB gene subfamily.The key genes involved in regulating the biosynthesis of flavonoids were excavated in Z.bungeanum,which provide a basis for exploring the mechanism of flavonoids in Z.bungeanum.The main results are as follows:(1)A total of 270 MYB genes were identified in ZBM,which were divided into three subfamilies according to the characteristics of the domains: 8 MYB related types,251R2R3-MYB types and 11 R1R2R3-MYB types.Among them,R2R3-MYB(ZbMYB)is divided into 33 subfamilies.The transcription factor proteins related to the flavonoid biosynthetic pathway are mainly concentrated in the S4,S5,S6 and S7 subfamilies.The members of ZBM MYB gene family are randomly and unevenly distributed on the chromosomes,accompanied by a large number of gene clusters.In the ZBM genome,72 collinear ZbMYB gene pairs were identified,and there were 29 ZbMYB duplicate pairs.The transposition replication event plays a major role in the expansion of the ZBM MYB gene family.Subcellular localization analysis predicts that most ZbMYB genes are located in the nucleus.(2)The accumulation of total flavonoids in different developmental stages of ZBM fruit has gone through two stages: "rapid increase and slow increase",and the trend of anthocyanin content is "decrease-rise-decrease".The content of total flavonoids and anthocyanins in ZBM reached the highest in the P70 stage,which were 23.613mg/g and0.235mg/g,respectively.High performance liquid chromatography(HPLC)analysis showed that the highest content of catechin was 0.413mg/g,and the lowest content of quercetin(0.071mg/g).(3)The ZbMYB gene of ZBM was expressed in a large amount in the early development of ZBM fruit,and showed a unique temporal and spatial expression pattern,and the flavonoid composition and content of ZBM at different developmental stages were different from the transcript abundance level of ZbMYB gene.Relevance.Combined with phylogenetic tree analysis,four fragments of prickly ash flavonoid biosynthesis related genes were finally discovered: EVM0027718,EVM0033809 and EVM0042160 genes may be involved in the synthesis of anthocyanins,and EVM0021667 may be the flavonoid synthesis genes CHS,CH1,F3H and FLS.