苍术属植物6个居群的染色体核型分析

Chromosome Karyotype Analysis of Six Populations in Atractylodes DC.

采用常规根尖压片法对苍术属植物6个居群染色体数目和核型进行分析。结果表明,所研究的苍术属植物居群染色体数目均为24条,核型公式分别为:保康居群2n=2x=10m+12sm+2st、商洛居群2n=2x=14m+10sm、岳西居群2n=2x=12m+12sm、英山居群2n=2x=14m+10sm、信阳居群2n=2x=14m+8sm+2st、神农架居群2n=2x=8m+10sm+4st。除了英山居群苍术核型为2A型外,其他的均为2B型。表明英山苍术是6个居群中比较原始的类群,而其他居群进化程度较高。同时根据6个居群的核型分析和Q型聚类结果可知,英山居群罗田苍术与商洛居群北苍术着丝粒核型相同,聚为一小类,再与信阳居群北苍术聚为一大类,认为将英山居群罗田苍术与其他苍术划分开来作为一个新的变种不合适;保康和岳西居群均为南苍术,聚为另一类,因此本研究结果支持北苍术作为苍术的一个变种,支持罗田苍术与南苍术、北苍术共同构成苍术属的一个分支——苍术复合体。神农架苍术居群单独聚为一大类,与其他居群的苍术亲缘关系较远,可能与其海拔高、生境复杂及与其他居群基因交流有限而导致遗传隔离有关,其他5个居群聚为另一大类,表明其遗传亲缘关系比较近,基因交流比较频繁。

Six populations of Atractylocles DC. （Compositae） were used to analyze their chromosome number and karyotype by applying root tip squash method. The results showed that chromosome number in all six popula- tions of Atractylocles spp. was 2n = 24 and the karyotype formulas were as follows： Baokang population 2n = 2x = 10m ＋ 12sm ＋ 2st, Shangluo population 2n = 2x = 14m ＋ 10sm, Yuexi population 2n = 2x --- 12m ＋ 12sm, Yingshan population 2n = 2x = 14m ＋ 10sin, Xinyang population 2n = 2x = 14m ＋ 8sin ＋ 2st, Shennongjia population 2n = 2x = 8m ＋ 10sin ＋4st. All of karyotypes for the investigated populations were 2B type but Yingshan population with 2A type,which showed that Yingshan population plant belonged to a relatively primitive type and relatively ancient or the primitive plant in evolutionary processes of Atractylodes. According to the dendrogram of Q analysis and karyo- type analysis of Atractylodes plant, Yingshan and Shangluo population plant was clustered into one sub-subgroup, whose centromere karyotypes were same, and Xinyang population plant which belonged to A. chinensis and the former two population plant was clustered into one subgroup, and Baokang and Yuexi population plant which belonged to southern A. lancea into another subgroup. The result don＇ t support A. lancea subsp. Lttotianensis treated as a sepa- rate new subspecies and Yingshan population plant should be A. chinensis plant, but support northern A. chinensis was a new subspecies of A. lancea. The results also showed that there was distant relationship between Shennongjiapopulation and other five ones. This might relate to its high altitude and complex habitats so that Shennongjia popu- lation plants had less gene exchange with them.