透過微斷層掃描機照射分析大岩桐花瓣形狀變異：輻射對稱和兩側對稱花朵的雜交系

Abstract

花瓣的形狀能夠決定花朵的外觀，因此花瓣的形狀在花卉園藝的領域裡一直是很重視的目標。不同發育情形下的花瓣能夠產生廣泛多變的花瓣形狀，因此研究花瓣的形狀變異也成為了探索花瓣發育不可或缺的研究。此研究的研究材料為第二子代的大岩桐花朵，第一子代花朵為透過將輻射對稱以及兩側對稱的親本雜交培育而成，而第二子代則是將第一子代進行自交而成。第二子代花朵的CYCLOIDEA基因組合型被觀察出與花朵形狀有非常大的關係，並且發育出具有相當大程度型態變異的花朵。為了能夠精確地描述花瓣形狀，此研究以微斷層掃描機掃描花朵取得三維花朵影像，並且透過三維型態學方法分析花瓣主要的形狀變異，透過觀察主要形狀變異定義出花瓣特徵，接著透過相關性分析以及階層式分群分析了解性狀協調，透過了解花瓣性狀的協調能夠了解花瓣發育上的趨勢，另外透過基因性狀關聯性的分析，我們也探討了在CYCLOIDEA基因組合型與花瓣特徵的關係，此外在輻射對稱的大岩桐花朵裡，觀察出背側花瓣有腹側化的現象，因此最後透過郝斯多夫距離量測形狀相似性以了解輻射對稱花朵的腹側化現象。

Study of petal shape variation is necessary for exploring petal morphology. Petals are complex in structures and vary tremendously. To describe petal shape accurately, three-dimensional (3D) methods were applied to this study. This study aimed to acquire 3D images using microcomputed tomography (μCT). 3D geometric morphometrics (GM) methods were used to evaluate major petal shape variations. The petal traits were physically identified according to the principal shape variations. The second generation (F2) populations of Sinningia speciosa (S. speciosa) resulting from intercross between a zygomorphic variety and an actinomorphic cultivar were applied to this study. The petal shapes of F2 population in S. speciosa were found largely associated with genotypic combinations of CYCLOIDEA (SsCYC) genotypes. The genotype-phenotype association was investigate to realize whether SsCYC genotypes played a key role in controlling the petal traits. The actinomorphic plants in S. speciosa developed flowers in which dorsal petals resembled the ventral petals. Venrtralization of the dorsal petals on actinomorphic plants was then examined morphologically by measuring the degree of shape similarity using Hausdorff distance. The 3D-GM methods approximately identified the petal shapes variations and defined the petal traits. Numerous petal traits, including petal width and left-right asymmetry of the dorsal petals, recurvation and petal size of the lateral petals, recurvation and lobe size of the ventral petals were identified not associated with SsCYC genotypes. The shape similarity analysis indicated that actinomorphic plants have ventralized phenotypes.