亚热带森林乔木树种DNA条形码研究——以哀牢山自然保护区为例

作为新一代植物志iFlora的重要组成部分，DNA条形码已经成为物种鉴定中重要且有效的方法。本研究以亚热带森林的乔木树种为研究对象，开展了DNA条形码的尝试性工作。为评估DNA条形码对鉴定亚热带森林树种的有效性，收集并研究了来自哀牢山自然保护区内5l科111属中204个树种的525个乔木个体。结果显示，所选4个DNA片段（rbcL，matK，trnH-psbA和ITS）的PCR扩增成功率都超过90％；测序成功率rbcL和matK最高，分别为90．7％和90．5％，trnH-psbA次之（83．6％），ITS最低（73．5％），表明4个片段在亚热带森林乔木中都具有较好的通用性。应用BLAST与NJ Tree两种方法，对物种和属水平的鉴别成功率进行统计，发现单片段中ITS最高，分别为68．4％-81．3％和99．0％～100％，核心条码rkL和matK组合的成功率是52．8％～60．2％和86．7％～90．5％，再与补充条码trnH-psbA和ITS联合，可以成功鉴别74．7％～79．6％哀牢山自然保护区亚热带森林中的乔木物种。由于ITS片段在亚热带森林部分重要树种类群（樟科和壳斗科等）中的测序成功率较差，所以对这些植物类群采用trnH-psbA作为DNA条形码是一个更好的选择。

DNA Barcoding of Subtropical Forest Trees --A Study from Ailao Mountains Nature Reserve, Yunnan, China

To evaluate how effective DNA barcoding is for the identification of subtropical forest trees, we sampled 525 individuals representing 204 species in 111 genera of 51 plant families that occur in the Ailao Mountains Nature Reserve, and tested the ability of rbcL, matK, trnH-psbA and ITS sequences to discriminate species. PCR success was over 90% for each of these four sequences, while sequencing success rate was highest for rbcL and rnatK （90.7% and 90.5% , respectively） , followed by trnH-psbA （83.6%）, and lowest for ITS （73.7%）. Thus, all four sequences showed a relatively high level of applicability for subtropical forest trees that occur in the Ailaoshan Mountains Nature Reserve. Using two different ＂species identification＂ methods - BLAST and Neighbor Joining （NJ）--the highest rate of success for identification at species （68.4%-81.3% ） and genus （99.0%-100% ） lev- els was obtained using ITS when only a single region was used. When two molecular regions were used in combina- tion, rbcL and marK correctly identified 52.8% -60.2% of species and 86.7% -90.5% of genera, while using all four regions in combination correctly discriminated 74.7% -79.6% of species. The relatively low sequencing suc- cess rate of ITS was mainly due to failure in certain groups （ such as Lauraceae and Fagaeeae） , which play an im- portant role in subtropical forest, suggesting that the ITS region may not be appropriate for DNA barcoding these par- ticular plant groups.