两个叶绿体基因位点的DNA条形码在桉属种间鉴定中的应用

 对桉属的13个样本(11个种、1个人工杂交种和1个优良无性系) 的trnH-psbA基因间隔区的序列进行了比对和分析, 13个桉属样本的trnH-psbA长度范围为538～576 bp, 序列排序的一致性长度为590 bp。共检测出了52个变异性状, 其中46个变异性状为碱基置换, 6个性状为插入或缺失。同时, 对桉属11个样本的rpl2-trnH基因间隔区(大单拷贝与反向重复接头) 区域进行了序列分析, 分析表明, 11个桉属样本的rpl2-trnH长度范围为79～149 bp, 序列排序的一致性长度为154 bp。共检测出了19个变异性状, 其中4个性状为插入或缺失, 15个变异性状为碱基置换。尾叶桉优良无性系的trnH-psbA和rpl2-trnH序列与尾叶桉仅1个位点的碱基置换; 与巨尾桉、巨桉进行比较, 尾叶桉优良无性系的trnH-psbA序列有27 bp 的插入, 以上4 个近缘样本在rpl2-trnH 区域的序列差异为12 个碱基置换。研究表明, 通过两个cpDNA基因位点序列不仅可以将桉属不同种进行区分, 而且也可以区分尾叶桉优良无性系与尾叶桉。因此,本研究涉及的两个叶绿体基因组位点序列在建立桉树植物种间鉴定的DNA条形码方面具有潜在的应用价值。

A Two-locus Chloroplast (cp) DNA Barcode for Identification of Different Species in Eucalyptus

In this study, sequences of trnH-psbA spacer were analyzed for 13 Eucalyptus samples. The trnH-psbA spacer of 13 Eucalyptus samples varied in length from 538 to 576 bp, and were aligned with a consensus length of 590 bp. Fifty-two mutations were scored in total. Six of these characters were indels, and 46 characters were substitution. The chloroplast genome of Eucalyptus, like that of most angiosperms, possesses inverted repeats (IR). The rpl2-trnH spacer, located at one of two junctions between the IRs and the large single copy (LSC) regions, was also sequenced from 11 Eucalyptus DNA samples. Sequences of rpl2-trnH were 79-149 bp in size, and were aligned with a consensus length of 154 bp. Nineteen mutations were scored in total. Four of these characters were indels. When compared with E. urophylla, only one mutation was observed in the rpl2-trnH spacer sequences of the elite clone (GL4). However, compared with E.grandis and E. grandis × E. urophylla, GL4 possessed a relatively large (27 bp) insertion in trnH-psbA intergenic spacer. Moreover, the sequences of rpl2-trnH among these four related samples show single-site mutations (12 in total). Extensive variation was found in the rpl2-trnH and trnH-psbA intergenic spacer (IGS) regions, suggesting that the sequences in this pair of loci have the potential to discriminate among the largest number of species or varieties of eucalypt for DNA barcoding purposes.