摘要： 对杉科（Taxodiaceae）与柏科（Cupressaceae s.s.）的28S rRNA基因的部分序列（约630 bp）进行PCR扩增、序列测定和系统发生关系分析，用简约法和邻接法构建的系统发生树基本一致。结果表明，杉科与柏科构成一个单系群，支持将杉科、柏科（Sciadopitys除外）合并为一个科——广义柏科（Cupressaceae sensu lato）的观点。在广义柏科中，Taiwania、Athrotaxis分别形成一支系；Metasequoia、Sequoia、Sequoiadendron关系较近，聚成一支系； Taxodium、Glyptostrobus、Cryptomeria聚成一支系；柏科聚成一支系。这一分析结果与叶绿体基因序列的分析结果相吻合，但是由于28S rRNA基因的进化速率较慢，尚不能分辨上述各个支系之间的系统演化关系。
Abstract:DNA sequences from 28S rDNA were used to assess relationships between and within traditional Taxodiaceae and Cupressaceae s.s.The MP tree and NJ tree generally are similar to one another.The results show that Taxodiaceae and Cupressaceae s.s.form a monophyletic conifer lineage excluding Sciadopitys.In the Taxodiaceae-Cupressaceae s.s.monophyletic group,the Taxodiaceae is paraphyletic.Taxodium,Glyptostrobus and Cryptomeria forming a clade(Taxodioideae),in which Glyptostrobus and Taxodium are closely related and sister to Cryptomeria;Sequoia,Sequoiadendron and Metasequoia are closely related to each other,forming another clade (Sequoioideae),in which Sequoia and Sequoiadendron are closely related and sister to Metasequoia;the seven genera of Cupressaceae s.s.are found to be closely related to form a monophyletic lineage (Cupressoideae).These results are basically similar to analyses from chloroplast gene data.But the relationships among Taiwania,Sequoioideae,Taxodioideae,and Cupressoideae remain unclear because of the slow evolution rate of 28S rDNA,which might best be answered by sequencing more rapidly evolving nuclear genes.