摘要
本文测定了山羊草属Aegilops 3个组中异源多倍体物种的核rDNAITS区序列 ,并用邻接法进行了聚类分析。结果表明 ,多倍体物种的ITS区序列长度为 559～ 60 6bp ,其中ITS1、ITS2分别有变异位点 51、42个 ,且存在多态位点。多倍体种均与各自的某一祖先种构成稳定分支 ,说明在杂交 多倍化后 ,这些多倍体的ITS区在同步进化的作用下已向着其某一祖先种的ITS区进化。对于sect.Vertebrata的异源多倍体物种来说 ,其ITS区主要向其祖先种Ae.umbellulata (UU)的ITS区进化 ,这与山羊草属的细胞遗传学研究结果基本一致。在sect.Cylindropyrum和sect.Polyeides中 ,Ae.cylindrica(CCDD)朝着Ae.caudata(CC)进化 ;Ae.ventricosa(DDMvMv)朝着Ae.comosa (MM)进化 ;Ae.vavilovii(DDMMSS)朝着Ae.crassa(DDMM)进化。
Hybridization with subsequent polyploidy is a prominent process in evolution of higher plants,but few data address the evolution of homeologous sequences after polyploidy.The internal transcribed spacer (ITS) of nuclear ribosomal DNA (nrDNA) from eleven allopolyploid species in Aegilops was investigated by PCR amplification and direct sequencing. The sequences obtained were used to study the evolution of ITS region in allopolyploid species. The length of ITS region varied from 599 to 606 bp and the number of variable sites was 93, i.e. 51 and 42 for ITS1 and ITS2 respectively. Some polymorphic sites were observed in polyploid species, and this indicated that the ancestral sequences had not been homogenized completely by concerted evolution. Distance matrix analysis of diploid and polyploid species by neighbor joining method, using Triticum monococcum as outgroup, resulted in well resolved neighbor joining tree indicating that the ITS regions of UUMM and UUSS genome (sect. Vertebrata) were homogenizing toward those of UU ancestal genome. This result is in agreement with the results of ctyogenetics of Aegilops. On the other hand, the neighbor joining tree including the D genome group species (sect. Cylindropyrum and sect. Polyeides) comprised three clades (CC DDCC, UU DDMM DDMMSS DDMMUU and MM DDM vM v), which suggested that concerted evolution was homogenizing the ITS region of the polyploid derivatives to either of their ancestors.
出处
《植物分类学报》
CSCD
2000年第3期211-217,共7页
Acta Phytotaxonomica Sinica
基金
国家自然科学基金!( 3 9770 0 56)
武汉大学青年骨干教师基金资助项目&&
