| Forsythia suspensa(Thunb.)Vahl is a kind of perennial machaka.It has both economic and ecological value.F.suspensa is a heterostyly plant with dimorphic style.It has self-incompatibility and low seed setting rate among the same style.In this study,with the purpose of exploring the cytological reasons for long style elongation,paraffin section technique was used to observe the anatomical structure of style in Forsythia suspensa at the development critical stage of flower buds.Cytoplasmic genomic differences of F.suspensa were studied by chloroplast genome sequencing.The differential genes were selected by transcriptome sequencing at the critical developmental stage of heterostyly in F.suspensa.the gene expression of brassinosteroid(BRs)pathway that might be involved in the development of heterostyly was analyzed.And the key gene 734A1＿like2,which may be involved in the development of F.suspensa,was cloned.1.At the P < 0.01 level,the length of the style cells of heterostyly is significantly different in the flower buds scale abscission phase,squaring period,dew corolla phase.and the difference in cell width and cell number is not significant,and the number of cells on the vertical axis of the same period was not significant at the level of at P < 0.05.It shows that the main reason for the different changes of heterostyly is the significant elongation of style cells.2.Comparing the chloroplast genomes of heterostyly,it was found that the long style type are the same as short style type : there are 156386 bp,114 coding genes including 80 CDS,30 tRNA and 4 rRNA.Chloroplast genome is not a key factor in the development of heterostyly in F.suspensa,nor can it be used as a basis for distinguishing long and short style type of F.suspensa.3.The transcriptome of F.suspensa was assembled to 86156 Unigenes at the critical development stage,Q30 ≥ 93.05% and and the assembly integrity was high.A total of 9868 differentially expressed genes were selected and annotated to 11 Unigenes related to BR metabolic pathway in heterostyly,and some genes were differentially expressed.4.In the BR metabolic pathway,the seven genes in the synthesis process were generally up-regulated.The two genes 734A1＿like2 and 734A1＿like4 that catalyze the hydroxylation of BRs 26 are significantly different in the development of heterostyly,and their gene expression in short style type is the same as that in Primula.734A1＿like2 protein has a complete cytochrome P450 family domain.5.A complete CDS sequence of 734A1＿like2 gene was cloned in F.suspensa,which is 1587 bp and encodes 528 amino acids.734A1＿like2 protein is a hydrophobic protein with good stability.Eighteen high frequency codons of Fs734A1＿like2 gene were identified.The codons used preference A / T,but the preference was weak.By comparing the frequency of codon usage between Fs734A1＿like2 and common hosts in functional studies,it was found that A.thaliana was more suitable for its heterologous expression receptor,and Yeast could be used as the receptor for enriching the expression products of this gene. |
