中国苋属nrDNA的ITS序列分析及其系统学意义

运用ＰＣＲ直接测序法，对苋属（Ａｍａｒａｎｒｈｕｓ Ｌ．）１５个种及外类群鸡冠花（Ｃｅｌｏｓｉａ ｃｒｉｓｔａｔａ Ｌ．）ｎｒＤＮＡ的ＩＴＳ区（包括ＩＴＳ－１，５．８５ｒＤＮＡ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６２９－６３２ｂｐ，长度变异仅发生在ＩＴＳ－１区（２５０－２５３ｂｐ）。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（ｓｅｃｇ

Sequence Analysis of the ITS Region of Nuclear Ribosomal DNA (nrDNA) in Chinese Amaranthus and Its Systematic Utility

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 .