絲瓜屬作物遺傳歧異性之分析

Genetic Diversity among the Lines and Cultivars of Luffa Species

本試驗的目的是利用群集分析及主成分分析RAPD分子標誌及形態性狀來鑑定圓筒絲瓜和稜角絲瓜品種（系）的遺傳歧異性。20個引子產生123個多型性條帶，根據分析結果，圓筒絲瓜與稜角絲瓜相似性僅0.17，二者具有高度的遺傳歧異性；種間雜交種與圓筒絲瓜群和稜角絲瓜群近乎等距，顯示種間雜交種的遺傳組成介於二親之中，並不偏向任一親；利用分子標誌檢測回交後代與圓筒絲瓜群和稜角絲瓜群的親緣關係，其相似度也符合該回交後代遺傳背景。參試的稜角絲瓜品種（系）間，遺傳歧異度較大；而參試的圓筒絲瓜品種（系）間，多型性條帶不多，分析結果顯示相似性高，遺傳差異並不大，但仍可分為主要二群，而從中國大陸收集的品種皆被分於同一群。分析圓筒絲瓜外表性狀，顯示果實性狀對圓筒絲瓜之群聚關係影響力較大；比較外表性狀與RAPD分子性狀的分析結果，二種分析所得之群聚關係有相似之處。RAPD技術配合群集及主成分分析可簡易的瞭解絲瓜屬作物遺傳歧異性，並可鑑別種間雜交種及其後裔的遺傳背景。對於圓筒絲瓜育種，由於遺傳差異小，建議優先加強國外圓筒絲瓜（或絲瓜屬）種原收集或利用國內種原與大陸種原或稜角絲瓜進行雜交，增加抗病性、提高品質及擴大遺傳基礎；稜角絲瓜的育種上則是應避免侷限使用特定材料，造成遺傳基礎窄化。 The objective of this study was to identify the genetic diversity among L. cylindrical and L. acutangula lines and cultivars through cluster and principal component analysis of RAPD molecular and morphological characters. One hundred and twenty three reproducible polymorphic PCR products were generated by the 20 selected primers. The genetic similarity between L. cylindrical and L. acutangula was 0.17 indicating that the two species were genetically diverted. The genetic distance between F1 interspecific hybrid and the two parental species were equal as evaluated by the molecular markers. Moreover, the genetic similarity of the backcross offsprings could be evaluated by the same system as well. The genetic diversity among the L. acutangula lines was greater than that among the L. cylindrical lines. However, the L. cylindrical lines still diverted into two groups and all the lines collected from Mainland China were clustered into the same group. The result of cluster analysis of the morphological characters conformed to that of molecular markers. Among the 19 morphological characters, fruit characters had more influence on clustering. The identification of genetic diversity, breeding background of L. cylindrical, L. acutangula, and the offsprings of their interspecific hybrids can be easily achieved by application of RAPD along with cluster and principal analysis. The result of genetic analysis also suggested that the priority strategy in L. cylindrical breeding is to enlarge genetic base through the collection of L. cylindrical (or L. spp.) from abroad. The suggestion to L. acutangula breeding is not to limit the breeding material to cetain lines, for which might narrow down the genetic diversity.