Menzel Gerhard, Dechyeva Daryna, Wenke Torsten, Holtgräwe Daniela, Weisshaar Bernd, Schmidt Thomas
Institute of Botany, Dresden University of Technology, D-01062 Dresden, Germany.
Ann Bot. 2008 Oct;102(4):521-30. doi: 10.1093/aob/mcn131. Epub 2008 Aug 5.
The aim of this work was the identification and molecular characterization of novel sugar beet (Beta vulgaris) repetitive sequences to unravel the impact of repetitive DNA on size and evolution of Beta genomes via amplification and diversification.
Genomic DNA and a pool of B. vulgaris repetitive sequences were separately used as probes for a screening of high-density filters from a B. vulgaris plasmid library. Novel repetitive motifs were identified by sequencing and further used as probes for Southern analyses in the genus Beta. Chromosomal localization of the repeats was analysed by fluorescent in situ hybridization on chromosomes of B. vulgaris and two other species of the section Beta.
Two dispersed repetitive families pDvul1 and pDvul2 and the tandemly arranged repeat family pRv1 were isolated from a sugar beet plasmid library. The dispersed repetitive families pDvul1 and pDvul2 were identified in all four sections of the genus Beta. The members of the pDvul1 and pDvul2 family are scattered over all B. vulgaris chromosomes, although amplified to a different extent. The pRv1 satellite repeat is exclusively present in species of the section Beta. The centromeric satellite pBV1 by structural variations of the monomer and interspersion of pRv1 units forms complex satellite structures, which are amplified in different degrees on the centromeres of 12 chromosomes of the three species of the Beta section.
The complexity of the pBV1 satellite family observed in the section Beta of the genus Beta and, in particular, the strong amplification of the pBV1/pRv1 satellite in the domesticated B. vulgaris indicates the dynamics of centromeric satellite evolution during species radiation within the genus. The dispersed repeat families pDvul1 and pDvul2 might represent derivatives of transposable elements.
本研究旨在鉴定新型甜菜（Beta vulgaris）重复序列并对其进行分子特征分析，以通过扩增和多样化揭示重复DNA对甜菜基因组大小和进化的影响。
分别使用基因组DNA和甜菜重复序列库作为探针，对甜菜质粒文库的高密度滤膜进行筛选。通过测序鉴定新型重复基序，并进一步用作甜菜属Southern分析的探针。通过荧光原位杂交分析甜菜及甜菜组的另外两个物种的染色体上重复序列的染色体定位。
从甜菜质粒文库中分离出两个分散的重复家族pDvul1和pDvul2以及串联排列的重复家族pRv1。在甜菜属的所有四个组中都鉴定出了分散的重复家族pDvul1和pDvul2。pDvul1和pDvul2家族的成员散布在所有甜菜染色体上，尽管扩增程度不同。pRv1卫星重复序列仅存在于甜菜组的物种中。着丝粒卫星pBV1通过单体的结构变异和pRv1单元的散布形成复杂的卫星结构，在甜菜组三个物种的12条染色体的着丝粒上以不同程度扩增。
在甜菜属的甜菜组中观察到的pBV1卫星家族的复杂性，特别是在驯化的甜菜中pBV1/pRv1卫星的强烈扩增，表明该属物种辐射过程中着丝粒卫星进化的动态性。分散的重复家族pDvul1和pDvul2可能代表转座元件的衍生物。
