2008-09-152024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/682019摘要：兩側對稱花的演化發生，促進了傳粉專一性，進而加速了開花植物的種化速率。我們選擇非洲堇人為馴化過程的一個栽培變異做比較研究，來探討花瓣對稱性基因的功能與演化。野生非洲堇上背側兩枚花瓣較下腹側三枚花瓣小，為典型兩側對稱花。栽培變異的非洲堇不分背腹，五片花瓣均等大，轉變成輻射對稱花。由這些比較推測，栽培突變很可能是控制花瓣兩側對稱的CYCLOIDEA(CYC)基因產生變異所造成。經過我們實驗室初步的基因釣取及表現分析，發現在在突變成輻射對稱花的栽培種中 CYC 的表現量有不正常的增加現象，我們進一步發現另一個花瓣對稱基因RADIALIS (RAD) 對 CYC 負回饋控制似乎也出現了異常。為了確認 CYC與RAD這些對稱基因的功能，我們計畫定位表現(In-situ hybridization)這些基因在花原基中背腹側花瓣表現的確切位置，並進一步構築載體分別將各個基因以35S啟動子過量表現在阿拉伯芥中，觀察其如何影響轉殖植物花對稱性及花瓣形態，這些基因的啟動子也將另外接上GUS觀察在轉殖植物花的表現位置。為更深一層探討這些基因的功能，我們預計將這些基因片段另外構築成 silencing vectors，利用TRV病毒轉殖回非洲堇中，以確認花對稱性基因表現缺失時是否會讓兩側對稱花逆轉變成輻射對稱花。由於CYC是花對稱性調控關鍵的主要基因，先前在金魚草中證實其可能受到其他開花基因的調控，我們將更深入地利用yeast one-hybrid作用在花芽expressed cDNA library上的方式來廣泛搜取所有會和CYC交互作用的基因蛋白質，希望由這些結果推演出非洲堇花瓣兩側對稱的基因調控方式，進而比較自然物種是否利用相似於模式植物的分子發育機制來調控花瓣對稱性。 <br> Abstract: The evolution of floral dorsi-ventral asymmetry (zygomorphy) has been well known in facilitating pollination specificity and speciation rate. A peloric mutant arose during African violet (Saintpaulia ionantha) domestication provides us a great opportunity to study the evolution and developmental mechanism about the conversion of flower symmetry. The peloric mutant of Saintpaulia differs from the zygomorphic wild-type in having all five petals identical in shape and size resulting a radial symmetry flower (actinomorphy). The peloric flowers appear to have lost their dorsal identity. The genetic basis of loss of floral zygomorphy has been demonstrated by the control of CYCLOIDEA (CYC) gene in model plant Antirrhinum majus L.. Based on this, we have first identified two Saintpaulia CYC (SaCYC) homologous genes in both wild-type and peloric mutant. SaCYC expression in peloria appears to be normal except the expression is somewhat up-regulated. Further analysis found that the mutation responsible for peloria is probably also related to another Saintpaulia dorsal identity gene RADIALIS (SaRAD), which is providing some negative regulatory feedback. To further analyse the interactions of these floral symmetry genes, we propose to conduct in-situ hybridisation to localize the expression domain of SaCYC and SaRAD along the flower dorso-ventral axis. In addition, each gene will be ectopically expressed in transgenic Arabidopsis to observe the phenotypic conversion. To characterise the promoter role, we will also make SaCYC and SaRAD promoter-GUS construct into transgenic Arabidopsis to check their expression normality. The way ultimately to approve gene’s phenotypic effect is to knockdown the gene function. We will use tobacco rattle virus (TRV) virus-induced gene silencing method in Saintpaulia to confirm the function of SaCYC. In Antirrhinum, it was proposed that other flower developmental genes might interact with CYC. As the regulating of SaCYC is the key element in maintaining flower zygomorphy, we therefore will utilize the yeast one-hybrid screening technique on Saintpaulia flower cDNA library in an attempt to identify proteins potentially interacting with SaCYC. By this way, we hope to better characterize the SaCYC regulating network in African violet.花對稱性基因病毒基因靜默技術兩側對稱輻射對稱Flower symmetry geneVIGSCYCLOIDEARADIALISDIVARICATA