Research Of Flower Buds Growth Development And The Mechanism Of Style-Length Dimorphism In Forsythia Suspensa

Forsythia suspensa is a perennial plant of the Forsythia genus.Its fruit have the functions of clearing heat and detoxifying,reducing swelling and dispersing,evacuating wind and heat.Forsythia suspensa is a heterostyly plant,divided into long style(L-morph)and short style(S-morph).Flower with the same style has self-incompatibility.When wild Forsythia suspensa is tended and cultivated,the ratio of L-morph and S-morph plants is unreasonable,resulting in lower yields.In this study,firstly,the paraffin section technique and stereo microscope were used to observe Forsythia suspensa flower buds differentiation and flower organ development,and pollination tests were performed;the sequence polymorphism of Forsythia suspensa heterostyly was studied by SSR(Single sequence repeats)molecular marker technology;The internal reference genes of heterostyly at flower development were screened,and the CYP734A_like genes related to style elongation was analyzed based on the transcriptome data of the research group.The results are as follows:1.Forsythia suspensa flower buds differentiation and flower organ growth and development process included flower buds differentiation,dormancy,flower buds germination and expansion,flower buds scale abscission phase,squaring period,dew corolla phase,flowering stage.The flower buds differentiation process can be divided into these stages: initial differentiation,sepal primordium differentiation,petal primordium differentiation,stamen and pistil primordium differentiation,pistil and stamen formation,pollen grains formation.One year before flowering,there were no significant difference in flower buds differentiation and development of heterostyly.L-morph styles elongated and exceeded S-morph until scale abscission phase,the filament began to develop at squaring period,and the filament of S-morph are much longer than L-morph at dew corolla phase.The seed setting rate of intermorph mating was more than 50%,intramorph mating and was self-crossing was about 20% and 5%,respectively.2.The 16 SSR primers had clear amplified bands.A total of 7 common alleles and 68 unique alleles were amplified.Among them,the amplified sequences of 4 SSR primers in L-morph and S-morph were significantly different.3.Researching the genes expression level of Forsythia suspensa flower development period,FS-4(c52656.graph.graph_c0)and HIS were screened as the optimal internal reference genes at flower organ development stages.4.Using the transcriptome data of the research group and bioinformatics technology,26CYP734A_like genes were identified,and their coding proteins were mainly located in the cytoplasmic membrane and mitochondria,all of which contained the P450 superfamily conservative characteristic sequence and the heme binding domain.It was found that CYP734A_like18(c59030.graph_c0)and CYP734A1 of Olea europaea,CYP734A_like22(c66147.graph_c0)and CYP734A1 of Erythranthe guttata have a close relationship.During the elongation of the style,the expressions of the two genes were down-regulated in L-morph and up-regulated in S-morph.However,the results of transcriptome FPKM showed that the expression of CYP734A_like22 did not change significantly during the elongation of Forsythia suspensa heterostyly.KEGG annotation results indicated that genes related to the CYP734A1 enzyme included the CYP734A_like18 gene.