基于比较核型分析方法追溯百合族 (百合科) 二型性核型的起源

百合族具有非常一致的二型性核型，由4条长染色体以及20条短染色体组成。目前有两个假说解释其二型性核型的来源，着丝粒横裂和多倍化。但是，具体是哪一种机制起主要作用仍然不清楚。根据文献以及自己的实验结果，我们整理并重新分析了百合亚科和美德兰亚科所有属的核型资料。比较核型分析结果表明，来自单条染色体的特征、染色体臂数、核型不对称性以及染色体的相对长度诸方面的证据都支持着丝粒横列是百合族核型进化的主要机制，但不能排除其它的机制也在起着作用，如臂间倒位和易位。臂间倒位和易位可能在郁金香族的核型进化中起着主要的作用。另外，本研究还报道了三个种的核型，粗茎贝母 (Fritillaria crassicaulis)、准格尔郁金香 (Tulipa suaveolens) 和尖果洼瓣花 (Gagea oxycarpa)。

Tracing the Origin of the Bimodal Karyotypes of the Tribe Lilieae (Liliaceae) Based on Comparative Karyotype Analyses

The karyotypes of the tribe Lilieae are rather constant bimodal, which is composed of 4 longer and 20 shorter chromosomes. However，it remains unclear which mechanisms (centric fission or polyploidisation) might contribute to the origin of biomodality in this tribe. Here, we collected the published data for all genera of the Li-lioideae and Medeoloideae, and re-analyzed the karyotype data. The evidence of individual chromosome features, fundamental number (FN), karyotype asymmetry and chromosome relative length indicated that centric fission is the main mechanism underlying karyotypic evolution in the Lilieae. However, centric fission is not expected to occur in isolation, and different mechanisms of karyotype change, such as pericentric inversion and segment translocation, are not mutually exclusive. Pericentric inversion and segment translocation may have played major roles in the karyotype evolution of the Tulipeae. Additionally, the karyotype analyses are carried out for the first time in three taxa: Fritillaria crassicaulis, Tulipa suaveolens, and Gagea oxycarpa.