Enke N, Kunze R, Pustahija F, Glöckner G, Zimmermann J, Oberländer J, Kamari G, Siljak-Yakovlev S
Botanic Garden and Botanical Museum Berlin-Dahlem, Freie Universität Berlin, Berlin, Germany.
Dahlem Centre of Plant Sciences, Freie Universität Berlin, Berlin, Germany.
Plant Biol (Stuttg). 2015 Jul;17(4):775-86. doi: 10.1111/plb.12318. Epub 2015 Apr 9.
Plant genome size evolution is a very dynamic process: the ancestral genome of angiosperms was initially most likely small, which led to a tendency towards genome increase during evolution. However, findings in several angiosperm lineages demonstrate mechanisms that also led to genome size contraction. Recent molecular investigations on the Asteraceae genus Crepis suggest that several genomic reduction events have occurred during the evolution of the genus. This study focuses on the Mediterranean Crepis sect. Neglectoides, which includes three species with some of the smallest genomes within the whole genus. Crepis neglecta has the largest genome in sect. Neglectoides, approximately twice the size of the two species Crepis cretica and Crepis hellenica. Whereas C. cretica and C. hellencia are more closely related to each other than to C. neglecta the karyotypes of the latter species and C. cretica are similar, while that of C. hellenica differs considerably. Here, the karyotypic organisation of the three species is investigated with fluorescence in-situ hybridisation and studied in a molecular phylogenetic framework based on the nuclear markers Actin, CHR12, CPN60B, GPCR1 and XTH23. Our findings further corroborate the occurrence of genome size contraction in Crepis, and suggest that the difference in genome size between C. neglecta and C. cretica is mostly due to elimination of dispersed repetitive elements, whereas chromosomal reorganisation was involved in the karyotype formation of C. hellenica.
被子植物的祖先基因组最初很可能较小，这导致了在演化过程中基因组增大的趋势。然而，在几个被子植物谱系中的发现表明，也存在导致基因组大小收缩的机制。最近对菊科还阳参属植物的分子研究表明，在该属的演化过程中发生了几次基因组缩减事件。本研究聚焦于地中海地区的还阳参属疏忽组，该组包含全属中基因组最小的三个物种。还阳参在疏忽组中拥有最大的基因组，大约是还阳参和希腊还阳参这两个物种基因组大小的两倍。虽然还阳参与希腊还阳参的亲缘关系比与还阳参更近，但还阳参与还阳参的核型相似，而希腊还阳参的核型则有很大差异。在这里，我们通过荧光原位杂交研究了这三个物种的核型组织，并在基于核标记肌动蛋白、CHR12、CPN60B、GPCR1和XTH23的分子系统发育框架中进行了研究。我们的研究结果进一步证实了还阳参属中基因组大小收缩的发生，并表明还阳参与还阳参之间基因组大小的差异主要是由于分散重复元件的消除，而染色体重组则参与了希腊还阳参的核型形成。
