攀附性仙人掌品系之親源分析

Abstract

紅龍果(Hylocereus spp.)與黃龍果(Selenicereus megalanthus)是可供果實食用的攀附性仙人掌。近二十年來台灣大量引進紅龍果，種類繁多，包含H. undatus 、H. polyrhizus 、H. costaricensis，果肉顏色分別為白色、紫紅色、紅色，由於種間、屬間無雜交障礙，導致現有品系繁雜。本研究以RAPD分析現有攀附性仙人掌品系，並輔以形態性狀來探討品系間遺傳歧異度與親緣關係。自188個逢機引子組中，篩選出39個引子，對78個攀附性仙人掌品系進行PCR反應，共增幅出398個條帶，其中181個是多型性條帶，占總條帶數的45.5%。經群集分析建立聚類樹狀圖，遺傳相似度在0.58時，Hylocereus 屬大致可區分為三群，H. undatus、H. polyrhizus、H. costaricensis、以及一個形態很特殊的品系，分群結果與形態分類結果相符合。群內有些品系兼具其他種的形態特徵及專一性條帶，推測是種間雜交後代。然而，S. megalanthus與Hylocereus 屬的遺傳相似度達0.40且與Hylocereus spp.具有217個共有條帶，有可能是屬間雜交親合的分子標誌佐證。此外，RAPD分析結果篩選出具種與品系的專一性條帶，可供雜交親緣追溯或品系鑑定之用。

Abstract In the last two decades, a great number of lines in Hylocereus were introduced into Taiwan including lines in H. undatus, H. polyrhizus, and H. costaricensis. The most distinct character among H. undatus, H. polyrhizus, and H. costaricensis are their flesh color, white, purple and dark red, respectively. Due to interspecific and intergeneric hybridization, the Hylocereus collection in Taiwan is very diverse. The objective of this study was to analyze the genetic relationship among 76 Hylocereus, 1 Selenicereus, and 1 intergeneric line between Hylocereus and Selenicereus through RAPD and morphological characters. In the RAPD analysis, 39 selected primers generated 181 (45.5%) reproducible polymorphic and 217 (54.5%) monomorphic bands. The dendrogram generated by cluster analysis based on 181 polymorphic bands resembled the morphological classification. At similarity coefficient 0.58, the Hylocereus genera were diverted into three main groups and one individual line. The morphological characters of the three groups resembled H. undatus, H. polyrhizus, H. costaricensis, respectively. However, some of the lines within each group were observed with some specific morphological characters and species-specific PCR products that belonged to another group. These lines were highly suspected to be the offspring of interspecific hybrids. The similarity coefficient between S. megalanthus and Hylocereus was 0.40. Such high similarity might be the molecular indication of low incongruity while doing intergeneric cross. Moreover, generic specific PCR products were identified and could be used to trace for the genetic background of some special lines in the collection.