Cloning And Functional Identification Of Chrysanthemum CmGATA12

Chrysanthemum morifolium is known as the top ten traditional flowers in China because of its high ornamental economic value.The natural flowering period of Chrysanthemum is mostly concentrated in the autumn,and the flowering period is concentrated,which is greatly influenced by the photoperiod and can not meet the current market demand.Therefore,in order to improve the annual supply capacity of chrysanthemum,improving the flowering time has always been the key of chrysanthemum breeding.Branching is one of the important horticultural traits of chrysanthemum,directly affects its cultivation methods and ornamental quality.At present,the physiological mechanism of chrysanthemum branching has been explored,but its genetic mechanism is still not clear.The study on flowering mechanism and branching regulation mechanism of chrysanthemum will provide important theoretical basis for molecular breeding of chrysanthemum flowering time and plant architectur.Studies have shown that GATA transcription factors can affect seed germination,seedling growth,regulate plant flowering and respond to environmental stress.However,GATA gene has not been cloned from chrysanthemum yet.Therefore,in this study,chrysanthemum 'Qing-Lu' was used as the plant material,the role of CmGATA12 transcription factor in flowering and branching regulation has been t preliminary explored hrough the methods of gene cloning,genetic transformation and other methods,which could lay the foundation for further research and breeding utilization of GATA transcription factors regulating florescence and shoot branch molecular mechanism in chrysanthemum.The main content and conclusions are as follows:1.The CmGATA12 gene was cloned,and the expression of CmGATA12 gene was detected in different tissues of chrysanthemum,and the subcellular activation and transcription activity of the CmGATA12 gene was studied.It was found that the CmGATA12 gene expressed in different tissues in chrysanthemum.And subcellular localization shows that the CmGATA12 is not only located in the nucleus but also located at the cell membrane and the CmGATA12 has transcriptional activation activity.2.By comparing the flowering time of wild type Arabidopsis thaliana and CmGATA 12 transgenic Arabidopsis and the number of rosette leaves,combined with the analysis of the flowering time related genes in CmGATA12 transgene plants and wild-type Arabidopsis thaliana.The experimental results showed that the flowering time of CmGATA12 transgenic Arabidopsis plants was ahead of wild-type Arabidopsis plants and the average flowering days were 8.7 days earlier than wild type plants.The number of rosette leaves at the time of flowering was less than that of wild-type Arabidopsis plants,the average number of rosette leaves is 1.9 lesser than that of wild type Arabidopsis plants.The expression levels of AtGI and AtSPL5 in flowering genes was up-regulated in CmGATA12 transgenic lines compared to wild-type Arabidopsis.The expression of AtGI was 1.6-1.8 times that of wild-type plants,and the expression of AtSPL5 was 1.3-1.6 times that of wild type.The expression of AtSVP,AtFRI,AtTOEl and AtTOE2 in CmGATA12 transgenic lines were significantly down-regulated.The expression of AtSVP was down-regulated by 0.4-0.7 times than that in wild-type Arabidopsis;the expression of AtFRI was down-regulated by 0.4-0.6 times as much as that in wild-type Arabidopsis;the expression of AtTOEl was down-regulated by 0.3-0.4 times as much as that in wild-type Arabidopsis;The expression level of AtTOE2 was 0.5-0.6 times lower than that of wild type.The results indicated that CmGATA12 has the function of promoting flowering of plants.3.By comparing the number of branches between wild-type Arabidopsis and CmGATA12 transgenic Arabidopsis,combined analysis with the suppressing branching genes expression between CmGATA12 transgenic Arabidopsis and wild-type Arabidopsis.The results showed that the number of primary,secondary and tertiary branches of CmGATA12 transgenic Arabidopsis plants was greater than that of wild-type Arabidopsis.The primary,secondary and tertiary branches of wild-type Arabidopsis were 1.2,1.3 and 0.In CmGATA12 transgenic lines,the number of primary,secondary and tertiary branches of CmGATA12-6 was 3.4,2.6 and 3.3 in Arabidopsis;the number of primary,secondary and tertiary branches of CmGATA12-10 was 3.9,3.1 and 5.4 in Arabidopsis.Genes that inhibit branching including AtBRC1,AtBRC2 and AtMAX2 was down-regulated to some extent in CmGATA12 transgenic lines compared with wild-type Arabidopsis,especially in AtBRCl,which was 0.1-0.2 of wild-type Arabidopsis expression,and at AtBRC2 was down-regulated by 0.6-0.8 times as much as wild-type Arabidopsis.The expression of AtMAX2 was down by 0.4-0.5 times than that of wild-type Arabidopsis.It shows that CmGA TA12 has the function of improving plant branching.