摘要：目前已知許多的被子植物花部的基因調控，很可能都是經由所謂的ABC模式來控制。然而對於許多花部形態特異的植物，這個假說勢必要加以修正。本研究計劃為一系列研究植物類花瓣構造的先趨主題之一，利用在非模式植物中（如阿拉伯芥）的研究來探討不同植物中對於花部控制相關基因，其中參與的各基因與其表現的變異。目前對於植物類花瓣構造的調控機制雖然不是十分瞭解，但仍然很可能是由於原先控制花瓣的基因，在類花瓣構造的地方表現，而生成類似花瓣的構造。本研究即以茜草的玉葉金花為材料來研究類花瓣構造的調控機制。
玉葉金花（Mussaenda pubescens）是台灣低海拔中常見的植物之一，也廣泛的被栽植為觀賞花卉。玉葉金花這一屬的植物中，常可以見到花萼其中的一個裂片尖端膨大成一個外形類似葉子、但顏色為白色或紅色的構造，稱為葉狀萼片（calycophylls, 或floral semaphylls）。而玉葉金花名稱的由來，即源於它的花序中黃色的花瓣和白色的葉狀萼片而來。這些葉狀萼片不管在細胞形狀或細胞排列上，都與正常的花瓣類似，加上有著顯著的顏色，一般皆認為這些葉狀萼片在功能上與花瓣無異。因此本研究以玉葉金花為材料
Abstract: Genetic mechanisms of floral development are one of the most interesting topics since there is tremendous diversity in the flowers of angiosperms. The recent studies suggested that all of the angiosperms may share similar floral development program, named ABC model. However, this basic model cannot explain all the features that exist in the diverse flowering plants. One of the possible modification of the basic model is the formation of a petaloid structure. Petaloid structures are found in many flowering plants, and can be classified as extrafloral petaloids, such as the showy bracts in dogwoods; and floral petaloids, such as the enlarged showy calyx-lobes in Mussaenda (Rubiaceae). The showy calyx-lobes, so called calycophylls, are mostly leaf-shaped, but have many petal features, such as bright color, papillate epidermis, and loose mesophylls. There are several hints that the formation of petaloid structures might be caused by different interactions, or change of function, among the floral related genes. Based on recent molecular studies on floral genes in Arabidopsis, the petaloidy could be simply explained by an ectopic expression of genes that control petal development, because overexressing petal identity genes can convert leaves to petaloid structures in Arabidopsis thaliana. Therefore, the showy bracts of dogwoods, or the calycophylls of Mussaenda could be controlled by petal-related genes. Our approach is to identify and characterize the petal-controlling genes in Mussaenda pubescens, a common plant in lowland Taiwan. Secondly, we will examine the expression patterns of these genes, to see if they are the reason of the enlargement of calyx lobes. We will also identify other expressed homeotic genes from different stages of the formation of calycophylls. Our result will compare with the studies of dogwood petaloid bracts, another on-going project in my lab. It will certainly provide great information about the evolutionary developmental programs of flowers and have many applications on other ornamental plants.
