Isolation And Function Analysis Of Floral Symmetry Gene In Chrysanthemum Morifolium ’Maoxiangyu’

Floral Symmetry is an important character of plants which has significant effect on pollinators attraction and pistil and stamen protection, commercial improvement also well. Chrysanthemum, due to its unique capitulum, which contain ray floret and tubiform floret, the ray floret is zygomorphy pattern and the tubiform floret is actinomorphy pattern. In recently years domestic and foreign researches of flower symmetry were focused on developmental biology, pollination biology and reproductive biology, the key point was focused on the exploration of petals morphogenesis the molecular mechanisms.In this paper, RT-PCR and RACE strategy was used to clone gene from Chrysanthemum morifolium ’maoxiangyu’ petals, a floral symmetry gene named CmDⅣ was cloned, Real-time PCR was used to analysis the expression pattern of the gene in different tissues and organs, the gene was transformed into Arabidopsis and phenotype was observed to study the gene functions. The main conclusions are as follows:1. Using RT-PCR and RACE strategy, a floral symmetry gene, named CmDⅣ was cloned from the petals of Chrysanthemum morifolium ’maoxiangyu’, the GeneBank accession number is KU871013. Bioinformatics analysis showed that the gene had an ORF of 879bp and encoded a protein of 292 amino acids, Quality of protein molecules are 32.83kD, isoelectric point is 9.16, molecular formula is C2632H4387N879O1104S138. CmDIV protein showed 55-70% similarity to other floral symmetry DⅣ protein in other plants by phylogenetic tree analysis. The CmDIV protein contain two SANT structural domain, is a kind of typical R2R3MYB transcription factor.2. Real-time PCR analysis showed that CmDⅣ had highest expression quantity in tubiform floret, the expression quantity in inflorescence stem and bract were followed, CmDⅣ had only one third expression quantity in ray floret compared its in tubiform floret. CmDIV also expressed in vegetative organ leaf and stem, which were a little lower than its in ray floret. Real-time PCR analysis in two wild species and three varieties showed that CmDIV had higher expression quantity in tubiform floret than its in ray floret, which showed that CmDIV played a role in chrysanthemum floral symmetry, and played a larger role in tubiform floret development.3. The plant expression vector PCAMBIA1304-DIV was constructed, the Agrobacterium tumefaciens infection was used to transferr CmDIV into Arabidopsis thaliana. Hygromycin selection was used and 4 transgenic plants was slected, RT-PCR showed that CmDIV was transferred into Arabidopsis. Phenotypic observation showed that transgenic Arabidopsis plants were lower and smaller compared to wild type, the leaves were smaller and rounder than wild type, floral symmetry were still actinomorphy, other properties were almost the same with wild Arabidopsis. We speculated that CmDIV gene involved in the regulation of floral symmetry is relatively weak. The reason phenotypic difference was not significant might be the redundancy or the differentiation of this CmDIV gene function.In this study we cloned and analysis a floral symmetry gene CmDIV from Chrysanthemum morifolium ’maoxiangyu’, RT-PCR analysis and transgenosis were conducted to study gene function. By all these we provided a better understanding of the floral symmetry in chrysanthemum and provided a basis for further exploration of floral symmetry regulatory mechanisms.