大穗看麦娘与日本看麦娘的DNA条形码鉴定

大穗看麦娘是我国麦田新发生的恶性杂草,与日本看麦娘苗期形态相近,导致难以识别和有效监测。本研究利用4个DNA 条形码候选序列(rbcL、matK、trnH-psbA和ITS2)对13份大穗看麦娘和10份日本看麦娘叶片材料进行分子鉴定,采用Vector NTI分析扩增的DNA序列峰图质量并比对碱基差异,通过MEGA 6.0软件中的K2P模型计算样本种内和种间的双参数遗传距离,采用邻接法构建系统发育树。结果表明,4个DNA 条形码序列中仅matK扩增测序结果不理想。日本看麦娘在4种DNA条形码序列中不存在种内差异,大穗看麦娘在rbcL、matK和ITS2序列中无种内差异,仅在trnH-psbA序列中存在7个差异位点。大穗看麦娘和日本看麦娘种间各DNA条形码序列均有差异,trnH-psbA、rbcL、matK和ITS2序列存在的差异位点数分别为6、3、14和28。ITS2的种间平均遗传距离大于rbcL,且具有特异性,适宜用于大穗看麦娘和日本看麦娘的准确鉴定。

Identification of Alopecurus myosuroides and A.japonicus by DNA barcode

Alopecurus myosuroides is a new emerging worst weed in wheat fields and has similar seedling appearance to A.japonicus. Screening DNA barcode for molecular identification of A. myosuroides and A. japonicus is crucial for effective weed identification and monitoring. To distinguish the A. myosuroides and A. japonicus, four DNA barcode fragments, rbcL, matK, trnH-psbA and ITS2 were used for molecular identification of 13 A.myosuroides and 10 A. japonicus samples. The quality of sequence peak map was observed and base differences were compared by Vector NTI software. The two-parameter genetic distance (K2P) was calculated by MEGA 6.0 software, and the phylogenetic tree was constructed by neighbor-joining (NJ). The results showed that among the four DNA barcodes, only matK amplification sequencing was found to be unsatisfactory. There were seven locus differences in A. myosuroides for trnH-psbA, but no intraspecific difference for rbcL, matK and ITS2 in A. myosuroides and for all the barcoding sequences in A. japonicas. There were interspecific locus differences between A.myosuroides and A.japonicus, the numbers of different locus for trnH-psbA, rbcL, matK and ITS2 were 6, 3, 14 and 28, respectively. The average genetic distance of ITS2 was larger than that of rbcL, which also had specificity. ITS2 was suitable for accurate identification of A. myosuroides and A.japonicus.