台南白玉米自交系RAPD分析的遺傳歧異度與其F1雜種優勢之相關

Abstract

本研究之主要目的在探討台南白玉米自交系RAPD分析的遺傳歧異度與其F1雜種之雜種優勢的相關性。試驗以台南白族群所分離的13個自交系及其半全互交的78個F1雜種，及天然混合授粉之台南白(對照種)為材料，在1996年秋作(9月23日)種植於農試所試驗田進行農性狀調查及籽粒產量之評估，並進行13個自交系之RAPD分析。結果顯示所使用的13個台南白自交系間其農藝性狀及RAPD分析的DNA條帶都有明顯的差異存在。自交系所產生的RAPD多型性條帶經由Jaccard's公式計算，顯示自交系遺傳距離之變異介於0.42~0.722之間。同時亦發現自交系間Jaccard's傳距離與其相對的F1雜種(兩親本之和)之一般組合力(GCA)無相關存在Jaccard's傳距離與特殊組合力(SCA)及對照雜種優勢(Hck)間之相關達極顯著，其R2值分別為0.125及0.137。因此台南白玉米自交系間RAPD之遺傳歧異度對F1雜種籽粒產量之一般組合力、特殊組台力及對照雜種優勢的大小無法很有效的預測。 The objective of this study was to evaluate the genetic diversity of 13 maize inbred lines, and to determine the relationship between genetic distance of the parental lines and their single cross hybrid heterosis. The randomly amplified polym01Phic DNA (RAPD) technique was used. SIX of these lines came from the Taichung populations, and the rest of inbred lines derived from other seven different population were available in this study. The agronomic traits of the 78 single crosses by half-diallel cross and their 13 parental lines were evaluated in the fall of 1996 at TARI. One Tainan white open- pollinated population was the check. Forty different 10-primers were used to give a total of 646 reproducible amplification products, 547 (84.7%) of them being polymolphic. Genetic diversity was determined using Jaccard's similarity coefficient. The results of this study showed that the inbred lines had significant difference in phenotypic traits and DNA sequences. The range of genetic distance between parental lines was from 0.421 to 0.772. There was no relationship existed between genetic distance and general combining ability (sum of the parental lines)of grain dry weight. But a significant relationship between the specific combining ability (SCA) and standard heterosis value (Hck) of grain dry weight of hybrid on genetic distance. However their coefficient of determination (R2) are low. So that the RAPD genetic diversity isn't effective to predicted the combining ability and standard heterosis value (Hck) of grain dry weight.