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为评估线粒体COI基因作为根结线虫(Meloidogyne spp.)DNA条形码的适用性,对收集的25个根结线虫群体的线粒体COI基因进行扩增、测序,检测其扩增和测序成功率。将测序获得的COI基因序列与Q-bank中下载的根结线虫COI基因序列共同进行比对分析,利用MEGA 6.0计算种内、种间遗传距离进行“Barcoding Gap”检验以及构建NJ系统进化树作聚类分析,检验COI基因对根结线虫的物种识别能力。结果表明:线粒体COI基因扩增和测序成功率极高,扩增成功率达96%,测序成功率为100%。种间平均遗传距离为0.126,远远超过种内平均遗传距离0.002的10倍,种内遗传距离与种间遗传距离存在明显的“Barcoding Gap”间隔区。系统发育分析显示,COI基因可有效分辨出本研究15种根结线虫中的10种,物种识别率约为67%。线粒体COI基因具有极高的扩增和测序成功率、较高的物种识别能力,且扩增片段长度适宜,符合物种鉴定DNA条形码基因的标准,可作为根结线虫候选条形码基因。
To assess the applicability of the mitochondrial COI gene as a DNA marker for Meloidogyne spp., Mitochondrial COI genes of 25 M. elegans populations were amplified, sequenced and their success rates for amplification and sequencing were determined. The sequence of COI gene was sequenced and compared with the COI gene sequence of Meloidogyne incognita downloaded from Q-bank. The intraspecific and interspecific genetic distances were calculated using the “Barcoding Gap” test and the phylogeny of NJ system Tree clustering analysis was performed to examine the COI gene’s ability to recognize root-knot nematodes. The results showed that the success rate of mitochondrial COI gene amplification and sequencing was extremely high, the success rate of amplification was 96% and the success rate of sequencing was 100%. The average genetic distance between species was 0.126, far more than 10 times the average genetic distance of 0.002 within the species. There was a significant “Barcoding Gap” interval between the intraspecific genetic distance and interspecific genetic distance. Phylogenetic analysis showed that 10 species of 15 root-knot nematodes were identified by COI gene effectively, and the species recognition rate was about 67%. Mitochondrial COI gene has a high success rate of amplification and sequencing, high species recognition ability, and the amplified fragment length is appropriate, in line with species identification of DNA barcode gene standards, can be used as root-knot nematode candidate barcode genes.