Karyotypes and Distribution of Tandem Repeat Sequences in Brassica nigra Determined by Fluorescence in situ Hybridization.

Whole-genome shotgun reads were analyzed to determine the repeat sequence composition in the genome of black mustard, Brassica nigra (L.) Koch. The analysis showed that satellite DNA sequences are very abundant in the black mustard genome. The distribution pattern of 7 new tandem repeats (BnSAT13, BnSAT28, BnSAT68, BnSAT76, BnSAT114, BnSAT180, and BnSAT200) on black mustard chromosomes was visualized using fluorescence in situ hybridization (FISH). The FISH signals of BnSAT13 and BnSAT76 provided useful cytogenetic markers; their position and fluorescence intensity allowed for unambiguous identification of all 8 somatic metaphase chromosomes. A karyotype showing the location and fluorescence intensity of these tandem repeat sequences together with the position of rDNAs and centromeric retrotransposons of Brassica (CRB) was constructed. The establishment of the FISH-based karyotype in B. nigra provides valuable information that can be used in detailed analyses of B. nigra accessions and derived allopolyploid Brassica species containing the B genome.

Wang GX ，He QY ，Macas J ，Novák P ，Neumann P ，Meng DX ，Zhao H ，Guo N ，Han S ，Zong M ，Jin WW ，Liu F ... -  《-》

Distribution of the tandem repeat sequences and karyotyping in cucumber (Cucumis sativus L.) by fluorescence in situ hybridization.

We analyzed repeat sequences composition in the genome of cucumber inbred line 9930 using whole-genome shotgun reads. The analysis showed that satellite DNA sequences are the most dominant components in the cucumber genome. The distribution pattern of several tandem repeat sequences (Type I/II, Type III and Type IV) on cucumber chromosomes was visualized using fluorescence in situ hybridization (FISH). The FISH signals of the Type III and 45S rDNA provide useful cytogenetic markers, whose position and fluorescence intensity allow for easy identification of all somatic metaphase chromosomes. A karyotype showing the position and fluorescence intensity of several tandem repeat sequences is constructed. The establishment of this FISH-based karyotype has created the basis for the integration of molecular, genetic and cytogenetic maps in Cucumis sativus and for the ultimate genome sequencing project as well.

Han YH ，Zhang ZH ，Liu JH ，Lu JY ，Huang SW ，Jin WW ... -  《-》

Characterization of the centromere and peri-centromere retrotransposons in Brassica rapa and their distribution in related Brassica species.

Lim KB ，Yang TJ ，Hwang YJ ，Kim JS ，Park JY ，Kwon SJ ，Kim J ，Choi BS ，Lim MH ，Jin M ，Kim HI ，de Jong H ，Bancroft I ，Lim Y ，Park BS ... -  《PLANT JOURNAL》

ChIP-cloning analysis uncovers centromere-specific retrotransposons in Brassica nigra and reveals their rapid diversification in Brassica allotetraploids.

Wang GX ，He QY ，Zhao H ，Cai ZX ，Guo N ，Zong M ，Han S ，Liu F ，Jin WW ... -  《-》

Comparative genomic in situ hybridization (cGISH) analysis of the genomic relationships among Sinapis arvensis, Brassica rapa and Brassica nigra.

To further understand the relationships between the SS genome of Sinapis arvensis and the AA, BB genomes in Brassica, genomic DNA of Sinapis arvensis was hybridized to the metaphase chromosomes of Brassica nigra (BB genome), and the metaphase chromosomes and interphase nucleus of Brassica rapa (AA genome) by comparative genomic in situ hybridization (cGISH). As a result, every chromosome of B. nigra had signals along the whole chromosomal length. However, only half of the condensed heterochromatic areas in the interphase nucleus and the chromosomes showed rich signals in Brassica rapa. Interphase nucleus and the metaphase chromosomes of S. arvensis were simultaneously hybridized with digoxigenin-labeled genomic DNA of B. nigra and biotin-labeled genomic DNA of B. rapa. Signals of genomic DNA of B. nigra hybridized throughout the length of all chromosomes and all the condensed heterochromatic areas in the interphase nucleus, except chromosome 4, of which signals were weak in centromeric regions. Signals of the genomic DNA of B. rapa patterned the most areas of ten chromosomes and ten condensed heterochromatic areas, others had less signals. The results showed that the SS genome had homology with AA and BB genomes, but the homology between SS genome and AA genome was clearly lower than that between the SS genome and BB genome.

Mao S ，Han Y ，Wu X ，An T ，Tang J ，Shen J ，Li Z ... -  《HEREDITAS》