摘要
药用植物苍术(Atractylodes)为菊科苍术属多年生草本植物,分布于东亚,在中国的许多地区栽培,收获其根状茎干燥后作药用。苍术的繁殖方式有种子繁殖、分株繁殖、根茎繁殖。分类依据的形态特征主要是叶、花的不同,但其形态差别有限。报道的所有苍术属植物的染色体数均为2n=24,除罗田亚种外均包含2对随体染色体,且随体很小;在染色体类型(中部着丝粒、亚中部着丝粒、亚端部着丝粒染色体)及数目上有差异。在罗田苍术的染色体上检测到1对染色体带有5S r DNA位点,另外2对染色体带有45S r DNA位点,其中1对为随体染色体,故1对染色体上的45S r DNA位点没有表达而形成随体。在核型对称性方面,罗田苍术为原始的2A型,而其他苍术与白术的均为2B型。罗田苍术在染色体上的分化为其亚种的分类地位提供了细胞学证据。DNA序列及分子标记揭示了不同苍术类型间一定的遗传变异,为其分类及演化提供了分子证据。罗田苍术花粉母细胞的减数分裂过程中,染色体(2n=24)正常配对形成12个二价体,后期I均等分离,在两次分裂的后期和末期没有落后染色体及形成微核,最后产生较高比例的可育花粉,为其较高结实率及种子的高成活率提供了细胞学解释。其正常的减数分裂也保证了进行有性与无性繁殖苍术染色体数目的稳定性。
The medicinal plant Atrac tylodeswhich belongs to the Asteraceae family. These perennial herbal plants are distributed in eastern Asia and are cultivated in many regions of China,fortheir dry atractylodes rhizome is used as medicines. They can be reproduced and cultivated by seeds, division propagation and rhizome.The classifications of Atractylodesplants are based on theirlimited variations in leaves and flowers. All plants studied have 2n =24,including two pairs of satellited chromosomes except for one pair of the Luotian type from Hubei Province. The satellites of small size occur at low frequency. The chromosomes types （meta-/submeta-/subtelo-centromeric chromosomes） and their numbers varies in different plants.A single locus of 5S rDNA and two loci of 45S rDNA loci were identified and separated on different chromosomes for the Luotian type.Furthermore,the Luotian type keeps the more symmetric karyotype than all others. Its karyotype differentiation supports its taxonomic uint of subspecies.DNA sequences and molecular markers provide some new clues for the genetic variations and evolution of these plants.During the meiotic divisions of pollen mother cells for the Luotian type,thenormal chromosome pairing and segregation were performed and thus no laggards and micronuclei were formed. The pollen grains with high stainability were produced, which provided the cytological explanations for the high seed-sets and good seed viability of this plant type.The normal meiosis also ensured the stable chromosome number （2n=24） for different types of this plant which reproduced sexually and asexually.
出处
《湖北农业科学》
2015年第10期2309-2313,共5页
Hubei Agricultural Sciences
基金
国家科研重大专项课题(2012ZX09304006)
