六倍体多星韭的发现及多星韭种内倍性组成及演化的分析

Detection of Hexaploid and Mechanisms of Polyploidy Formation in Allium wallichii Kunth

采用染色体常规制片技术,对云南西北部和中部地区11个多星韭居群进行了细胞学分析。结果显示:(1)云南西北部多星韭二倍体、四倍体混合分布的太子阁和华首门四倍体居群中发现了三倍体(2n=3x=21),核型公式分别为:2n=3x=21=[6m(2sat)+8sm]+(3m+4sm)和2n=3x=21=[4m(2sat)+10sm]+(2m+4sm+lst)。三倍体含2条随体染色体,它的21条染色体含2个同源染色体组和一个与它们同源性稍差的染色体组。(2)在云南中部的多星韭四倍体居群中首次发现了六倍体,核型公式为2n=6x=42=15m(3sat)+27sm,核型类型2A。(3)结合核型特征及地理分布对多星韭三倍体和六倍体的成因进行分析,提示多星韭三倍体来源于二倍体与四倍体的杂交,六倍体是通过四倍体产生的未减数配子(n=4x=28)与正常减数配子(n=2x=14)的结合形成的。本研究结果支持多星韭的分化中心是云南西北部高海拔地区的观点,并结合前人的研究和本工作的结果,对多星韭种内的倍性组成和演化进行了分析和讨论。

In this study,we examined the chromosomes numbers and karyotypes of 11populations of Allium wallichii Kunth from the northwest and central region of Yunnan.（1）Triploid individuals were found in two tetraploid populations which grew near diploid populations.The karyotypes were 2n=3x=21=[6m（2sat）＋8sm]＋（3m＋4sm）and 2n=3x=21=[4m（2sat）＋10sm]＋（2m＋4sm＋lst）,respectively.（2） Hexaploid seeds were found in tetraploid population for the first time.The karyotype were 2n=6x=42= 15m（3sat）＋27sm.（3）Considering the karyotypes and cytogeographic information,it can be inferred that the triploid was formed via hybrid between diploid and tetraploid,while fusion of an unreduced tetraploid gamete（n=4x=28）with a reduced diploid gamete（n=2x=14）formed hexaploid.Our results supported that A.wallichii Kunth originated in the high elevation region of northwest Yunnan.In addition,combining both previous studies and our present results,we discussed the possible mechanisms of polyploidy formation in A.wallichii Kunth.