Preliminary Study On The Regulation Of Lateral Bud Development By Chrysanthemum CmDWF1

Chrysanthemum(C.morifolium)originated in China,is one of China’s top ten traditional famous flowers and one of the world’s four largest cut flowers,with high ornamental value and economic value,occupying an important position in the world flower industry.The types of branches of chrysanthemums are diverse.The number of branches,branch height,branch length and branching angle of different chrysanthemum varieties are quite different.It is an ideal material for studying plant branch formation.The branching type of chrysanthemum determines the cultivation method(single chrysanthemum,multi-headed chrysanthemum,etc.),production cost and ornamental quality.Therefore,the research on chrysanthemum branching has been a hot and difficult point in domestic and foreign research.Our previous study found that sucrose promoted the growth of chrysanthemum lateral buds,and CmDWF1 was up-regulated during this process.This study aimed to clone CmDWF1 and conduct a preliminary study on its regulation of lateral bud development,laying a foundation for enriching the developmental network of chrysanthemum branch development and cultivating new varieties related to branching.The main contents and results are as follows.1.CmDWF1 up-regulated the expression of sucrose in the growth of chrysanthemum lateral buds,but exogenous brassinolide(eBL)inhibited lateral bud growth,while brassinosteroid synthesis inhibitor(BRZ)treated lateral buds promoted lateral bud elongation.In order to study the effect of BR on the growth of chrysanthemum lateral buds,CmDWF1 was cloned and found to be 1692 bp in length,encoding 563 amino acids.The phylogenetic tree showed that CmDWF1 was closely related to LsDWF1 in lettuce.Subcellular localization experiments showed that CmDWF1 protein localization in the nucleus and in the cell membrane.Tissue quantification showed that the expression level of CmDWF1 in roots was higher,followed by stems,and the expression level in leaves was lower.The CmDWF1 promoter was cloned and found to be 1512 bp.Elemental analysis revealed that the promoter of CmDWF1 contained the sugar response element SURE1,WRKY response element,MYB response element,NAC response element,and EIN3 response element.2.To further verify the functionality of CmDWF1,we converted it to the chrysanthemum’Jin ba’.It was found that the transgenic chrysanthemum interfering strain of CmDWF1 showed a phenotype that promoted lateral bud growth.After the double stem segment of the interfering strains RNAi-10 and RNAi-11,the apical bud lengths of RNAi-10 and RNAi-11 were 4.29 mm and 4.98 mm,respectively,while the wild type ’Jin ba’(WT)was only 2.49 mm.The results indicated that the transgenic chrysanthemum interfering strain of CmDWF1 showed a phenotype that promoted lateral bud growth.Quantitative analysis of the transgenic chrysanthemum interference lines revealed that the BR synthesis genes CmDWF1,CmBR6oxBR and the signaling pathway genes CmBES1.1,CmBES1.2 and CmBZR1 were down-regulated,while the expression levels of sucrose transporter genes CmSWEET9,CmSWEET10 and CmSWEET11 were significantly increased.Therefore,it is speculated that under the condition of 20 mM sucrose,The CmDWF1 transgenic chrysanthemum interfering strain promoted lateral bud growth,which may be related to the up-regulated expression of sucrose transporters CmSWEET9,CmSWEET10 and CmSWEET11.