The sequences of the ITS region (including ITS-1, 5.8S rDNA and ITS-2) of nuclear ribosomal DNA from 15 species of the genus Amaranthus L. and outgroup Celosia cristata L. were determined. The result shows that the size of the ITS region of Amaranthus is from 629 to 632 bp, and the length variation is only found in ITS-1 (250-253 bp). On the basis of phylogenetic analysis of nucleotide sequences, the Amaranthus species in China may be devided into three sections, viz., sect. Spinosus, sect. Amaranthus and sect. Paucestamen; the cultivated species, viz., Amaranthus paniculatus L., A. cruentus L., A. caudatus L. and A. hypochondriacus L. can be treated as the subsp. of A. hybridus L.; A. taishanensis F.Z.Li and A. tenuifolius Willd are both closely related to species in the sect. Paucestamen. The study also indicated that the number of stamens has more phylogenetic information than other characters, such as the number of sepals and dehiscence/indehiscence of fruits in Amaranthus.
中国苋属nrDNA的ITS序列分析及其系统学意义
宋葆华1,2陈之端2 汪小全2 李法曾1*
（1. 山东师范大学逆境植物重点实验室，济南250014；
2. 中国科学院植物研究所系统与进化植物学开放研究实验室，北京100093）
摘要：运用PCR直接测序法 ,对苋属 (AmaranthusL .) 15个种及外类群鸡冠花 (Celosiacristata L .)nrDNA的ITS区(包括ITS_1,5 .8SrDNA和ITS_2 )进行序列测定。结果表明苋属植物的ITS序列总长度为 6 2 9～ 6 32bp ,长度变异仅发生在ITS_1区 (2 5 0～ 2 5 3bp)。采用PAUP软件进行系统发育分析表明 :分布于中国的苋属植物可分为 3组 ,即刺苋组 (sect.Spinosus) ,五蕊组 (sect. Amaranthus)和 2-3蕊组 (sect.Paucestamen) ;栽培种AmaranthuspaniculatusL .,A .cruentusL .,A .caudatusL .和A .hypochondriacusL .可作为A .hybridusL .的种下等级 ;新种A .taishanensisF .Z .Li和新分布种A .tenuifoliusWilld与 2_3蕊组 (传统 3被组 )关系密切。另外 ,研究结果分析表明 :雄蕊数目比花被片数目和胞果是否开裂等性状在苋属植物分类中更有意义。
关键词： 苋属；ITS区；分子系统发育；分类
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