以葉綠體基因組之非密碼區及核核糖體DNA之序列探討台灣地區鬼針草(Bidens pilosa L.)之遺傳多樣性

Abstract

According to the Flora of Taiwan, there are three varieties of Bidens pilosa L. They are var. radiata, var. minor and var. pilosa. To discover the genetic diversity and gene flow in different hierarchy (inter-varieties, intra-varieties, inter-populations and intra-populations) in these varieties, this study investigated 161 samples from these varieties comprising 11 different populations and 7 samples of Bidens biternata for out-group control. The internal transcribed spacer (ITS1 and ITS2) and the 5.8S of nuclear ribosomal DNA (nrDNA), trnL intron and trnL-trnF IGS loci of the chloroplast genome were amplified and sequenced in all samples. For further analysis, the sequences of ITS1, ITS2 and 5.8S were combined and aligned as nrDNA sequence which covered 637 bp. And the sequences of trnL intron and trnL-trnF IGS were combined as cpDNA with 799 bp alignment. It showed that the genetic diversity of nrDNA sequence was higher than that of cpDNA from the data of the number of polymorphic sites (S), number of haplotypes (H), gene diversity (Hd), nucleotide diversity (π) and genetic diversity (θ). The genetic distances (FST) of intra-populations and intra-varieties was with the following order, var. radiata ＜var. minor ＜ var. pilosa, and the gene flow (Nm) has shown var. radiata ＞ var. minor ＞ var. pilosa. From the results of the analysis of molecular variance (AMOVA), there are more than 50% variance contributed by the variance of ”within populations” in the loci of nrDNA and cpDNA. The rest were contributed by the variance of ”among varieties” and ”among populations within varieties”. The gene flow between var. radiata and var. minor or var. pilosa showed lower than those between var. minor and var. pilosa, it indicated the significant hybridization phenomenon between var. minor and var. pilosa which naturalized earlier than var. radiata.