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半蒴苣苔属植物染色体制片优化及染色体数目和倍性研究

Optimization of chromosome preparation and chromosome numbers and ploidy in Hemiboea

摘要:染色体数目和倍性是系统与进化生物学和遗传学研究中十分重要的基础信息。苦苣 苔科半蒴苣苔属(Hemiboea)植物具有重要的药用价值和观赏价值,约 44 种,主要分布于 我国南部地区。因其根系细小且相互缠绕以及染色体小型的特点,获取其根尖材料进行 染色体制片研究染色体往往比较困难。目前该属仅有 3 种的染色体数目被报道,绝大部分 种的染色体数目和倍性尚不清楚。染色体数目的进化模式与物种的进化关系亦不清楚。为 了探索该属染色体制片的适宜条件及染色体数目与物种的进化关系,本研究根据半蒴苣苔 属植物具有叶片扦插繁殖的特性,采用叶片水培生根法来获取半蒴苣苔(Hemiboea subcapitata)、弄岗半蒴苣苔(H. longgangensis)、龙州半蒴苣苔(H. longzhouensis)、江西 半蒴苣苔(H. subacaulis var. jiangxiensis)、华南半蒴苣苔(H. follicularis)和永福半蒴苣苔 (H. yongfuensis)6 种植物的根尖材料,探索了不同实验条件对染色体制片效果的影响,对 染色体制片实验的条件进行了优化并进行染色体计数,同时基于半蒴苣苔属染色体数目 的进化历史探讨染色体数目的进化模式及其与物种进化的关系。结果表明:(1)上午 9:30-10:00 取材,解离 10 min 以及染色 15 min 为半蒴苣苔属染色体制片的适宜条件;(2) 确定了半蒴苣苔属上述 6 种植物均为二倍体,染色体数目均为 32(2n=2x=32);(3)除个别 物种染色体数目有变化外,该属大部分物种染色体数目可能为 2n=2x=32,且染色体数目变 化可能是非整倍化的作用,与物种进化没有明显关系。本研究为半蒴苣苔属以及具有类似 叶片再生植株特性的类群的染色体制片提供了参考,并为该类群的分类,系统进化等方面 的研究提供了启示。

英文摘要:Chromosome numbers and genome ploidy are crucial basic information for evolutionary biology and genetics. Hemiboea, a genus of Gesneriaceae, with about 44 species, is mainly distributed in southern China, which have important medicinal and ornamental value. It is difficult to obtain suitable root tips for the chromosome preparation because of their small twining roots and small chromosomes. So far, only the chromosome numbers from three species of Hemiboea have been reported, while the chromosome numbers and ploidy of most species are unknown. The relationship between the pattern of chromosome number evolution and species evolution is also unclear. In this study, in order to explore the optimal conditions for chromosome preparation and the relationship between chromosome numbers and species evolution of Hemiboea, firstly, the root tips of six species (including H. subcapitata, H. longgangensis, H. longzhouensis, H. subacaulis var. jiangxiensis, H. follicularis, and H. yongfuensis), which were generated by the method of hydroponic rooting for cutting leaves based on the characteristics of leaf cuttage propagation of plants in the Hemboea, were used for the chromosome experiments. Then, we assessed the effects of different experimental conditions on chromosome preparation, and then, the conditions were optimized and the chromosome counting was performed. Finally, the evolutionary history of chromosome numbers in Hemiboea and the related genera including Anna and Loxostigma were traced based on the molecular phylogenetic relationships, and the evolutionary pattern of chromosome numbers and relationships with species evolution were studied. The results were as follows :(1) The optimal condition for karyotype preparation of the plants in Hemiboea are sampling during 9:30-10:00 am, dissociating for 10 min, and staining for 15 min. (2) All the six species of Hemiboea are diploid and with 32 chromosome numbers (2n=2x=32). (3) Except for a few species in the genus, the chromosome numbers of most species may be 2n=2x=32, and the variation of chromosome numbers may be caused by aneuploidy, which has no obvious relationship with the species evolution. This study shed light on chromosome preparation of Hemiboea and other groups with similar leaf regeneration characteristics, and provides implications for the classification and phylogeny of this group.

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[V1] 2022-08-05 16:38:28 chinaXiv:202208.00043V1 下载全文
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