| Chrysanthemum(C.morifolium)is Chinese traditional ornamental flower and it is one of world’s four largest fresh cut flowers with high ornamental value and economic value,favored by consumers and markets.Flower color is an important trait of ornamental plants.For some chrysanthemum cut flowers,the ornamental characteristics are easily affected by environmental factors.Flower color is an important trait of ornamental plants.For example,the pigments of some chrysanthemum cultivars fade in color due to heat stress.Through the analysis of transcriptome data from high-temperature processing,we found HY5 gene that may cause color changes in high-temperature environments.HY5 is a bZIP-type transcription factor that can affect anthocyanin synthesis in response to temperature changes in other species.In this study,CmHY5 was cloned from chrysanthemum Nannong Ziyunying’.The following research results were obtained by analyzing the color regulation functions of this gene.1.Spray chrysanthemum ’Nannong Ziyunying’ and ’Nannong Zizhu’ in summer high temperature environment appears reduction of petal anthocyanin biosynthesis.We detected the differential gene epressions in response to high temperature in the petal by using transcriptome sequencing.The results suggest structure genes and function genes in the pathway of anthocyanin metabolism,including CHS,CHI,DFR,F3H,ANS,3GT,F3’H were down-regulated.In addition,the expression level of MYB4,MYB17,MYB16,MYB114,MYBS3,PAP1,PAP2 in the MYB transcription factor that regulates the expression of flower color functional gene was down-regulated;bHLH transcription factor transcription factor AN1 was down-regulated,and the expression of WD40 protein coding genes COP1,SPA4 and TTG1 was down-regulated.The bZIP-type transcription factor HY5 was significantly down-regulated;the BBX family transcription factor BBX25 was up-regulated,and BBX20 was down-regulated.These transcript factors may synergistically inhibit the synthesis of anthocyanins at high temperatures.2.The transcription factor CmHY5 was analyzed in chrysanthemum "Nanong Ziyunying’(’NAZYY’)high temperature transcriptome.CmHY5 was cloned from chrysanthemum ’NAZYY’,with an open reading frame of 477 bp,which has high homology with HaHY5 in Helianthus annuus and MdHY5 in Malus domestica.CmHY5 is expressed in various tissues,but the highest expression level is in tongue flowers.CmHY5 has no transcriptional activation activity in yeast cells.Subcellular localization shows that CmHY5 is only distributed in the nucleus.With the decrease of CmHY5 expression at flowering stage,the flower color changed from purple to white.Fluorescence quantitative detection of flower color metabolic structural gene expression showed downregulation.It is speculated that under high temperature,CmHY5 positively regulates the color of chrysanthemum.With the mature genetic transformation system of Chrysanthemum’Nannong Fencui’,the CmHY5 in RNA interference vector was transformed,and 11 positive lines were obtained,which laid a foundation for further functional research. |
