DNA序列在植物系统学研究中的应用

植物DNA序列由于进化速率上的差异而适用于不同分类阶元的系统发育研究，因此，针对某一特定的系统学问题选择相应合适的分子片段是分子系统学研究中最为关键的一步。在前人研究的基础上，主要讨论了目前分子系统发育和进化研究中一些常用的DNA序列的适用范围，包括nrDNA的18S基因及ITS等非编码区，cpDNA的编码基因（rbcI、matK、ndhF、atpB）及非编码区序列（rpL16、rpoC1、rps16、trnL-F和trnT-L）和应用较少的mtDNA。研究表明，18S、rbcI等编码基因及mtDNA一般适用于较高分类阶元甚至整个种子植物谱系间的系统发育的探讨，而ITS及cpDNA的非编码区序列等因其较快的进化速率多用于较低分类阶元的系统关系研究。

Application of DNA Sequences in Plant Phylogenetic Study

DNA sequences,because of their disparity in the rate of evolution,are suitable for phylogenetic study at different taxonomic levels.It is,therefore,the most significant process to select an appropriate DNA region to address a certain phylogenetic issues.Based on previous data and our own study,the suitable range of some DNA sequences that are commonly used in current molecular phylogenetic study is mainly focused in this review.These sequences contain 18S gene and non coding regions (such as ITS) of nrDNA,coding regions ( rbc L, mat K, ndh F and atp B etc.) and non coding regions ( rpL 16, rpo C1, rps 16, trn L F and trn T L etc.) of cpDNA,and mtDNA,which is seldom used.It is inferred that,in general,the coding genes such as 18S, rbc L and mtDNA are likely informative to resolve phylogenetic issues ranging from higher taxonomic ranks to the relationships among seed plant lineages.The non coding DNA regions (such as ITS,introns and intergenic spacers of cpDNA) are presumed to be more useful at lower taxonomic levels because of their faster evolutionary rates.