Molecular and cytogenetic studies to estimate genome size reduction of chromosomal DNA in genus Aster

羽片花叶石竹的核型与紫花紫薇的核型相似。然而，羽裂金龟子的染色体尺寸(S型染色体)明显小于斑点金龟子(L型染色体)。和小头金鱼的杂交起源。卵形染色体(LS型染色体)是由细胞遗传学和叶绿体DNA数据推测的。叶绿体DNA的系统发育也表明S类型的染色体是无性型的。这意味着基因组大小的缩小发生在向羽扇形藻进化的过程中。在这项研究中，我们证明了染色体大小的差异并不取决于染色体凝聚的强度，而是取决于DNA含量。同时的GISH结果显示，S型染色体与小头金鱼相似。卵形，以及黑线姬松林和小头黄曲霉的L型染色体之间的差异。Ovatus，这为小头拟变种提供了进一步的证据。卵子是由S型染色体和L型染色体产生的四倍体双二倍体。TYL-COPIA类反转录转座子在L和S染色体上的分布规律相似。该反转录转座子的拷贝均匀地分布在所有染色体上，TYL-Copia类反转录转座子是否与它们之间的大小差异有关并不明显。

The karyotype of Kalimeris pinnatifida is morphologically similar to those of Aster ageratoides var. ageratoides, however, the size of the chromosomes of K pinnatifida is apparently smaller (S-type chromosomes) compared to those of A. ageratoides (L-type chromosomes). And the hybrid origin of A. microcephalus var. ovatus (LS-type chromosomes) is previously suggested by cytogenetics and chloroplast DNA data. The chloroplast DNA phylogeny also implies that the S type chromosome is apomorphic. It means genome size reduction happened on the evolutionary way to K. pinnatifida. In this study we demonstrated that the chromosome size difference do not depend on the intensity of chromosome condensation but the DNA contents. And the simultaneous GISH results here showed the similarity between S-type chromosomes of K pirmatifida and A. microcephalus var. ovatus, and between L-type chromosomes of A. ageratoides and A. microcephalus var. ovatus, which provided additional evidence for A. microcephalus var. ovatus being a tetraploid amphidiploid produced by the S-type chromosomes and the L-type chromosomes. The distribution patterns of Tyl-copia like retrotransposons were similar between L-and S-type chromosomes. The copies of this retrotransposon dispersed uniformly on all chromosomes, and it is not apparent if the Tyl-copia like retrotransposon concerned the size difference between them.