The physical location of 45S and 5S rDNA sites by double-target fluorescence in situ hybridization （FISH） and 5S rDNA non-transcribed spacer （NTS） sequences was studied in five accessions of Nelumbo nucifera Gaert...The physical location of 45S and 5S rDNA sites by double-target fluorescence in situ hybridization （FISH） and 5S rDNA non-transcribed spacer （NTS） sequences was studied in five accessions of Nelumbo nucifera Gaertn.and one accession of N.nucifera subsp.lutea （Willd.）.The chromosome number of all tested materials was 2n=16.The loci of 5S rDNA were close to the centromere regions of chromosome 3,and the loci of 45S rDNA were found on chromosomes 7 and 8 in all the six tested accessions,respectively.Similarly,45S rDNAs were also located on chromosome 4 in four tested accessions.The 5S rRNA gene sequences were conserved and the NTS sequences were variable among the samples.N.nucifera subsp.lutea was the longest branch in the phylogenetic tree and clustered with N.nucifera cv.Liangzihu.N.nucifera cv.Heilongjiang and N.nucifera cv.Weishanhu showed a close relationship with each other.N.nucifera cv.Dahe Lian was closer to N.nucifera cv.Nihelu Lian than to other tested accessions.Analysis of the molecular karyotype and the 5S rRNA gene spacer sequence suggested the genetic diversity was limited within Nelumbo species and it seems suitable that American lotus was considered as the subspecies of N.nucifera.展开更多
IGS is abundant in polymorphism,which is widely used in the analysis of intraspecific genetic diversity and phylogenetic relationships among geographical populations.In this study,the 45S rDNA repeat unit of Saccharin...IGS is abundant in polymorphism,which is widely used in the analysis of intraspecific genetic diversity and phylogenetic relationships among geographical populations.In this study,the 45S rDNA repeat unit of Saccharina japonica was obtained for the first time by BAC clone sequencing.The total length of the 45S rDNA repeat unit of S.japonica was 8995 bp,including 5420 bp of 18S-5.8S-25S rDNA,and 3575 bp of IGS(Intergenic Spacer),with the GC content of 51.4%.The IGS was composed of a 465 bp of 3′-outer transcribed spacer(ETS),an 874 bp 5′-ETS,and a 2236 bp non-transcribed spacer(NTS),with the GC content of 50.1%.Fiber-FISH(fiber-fluorescence in situ hybridization)analysis of the distribution of 45S rDNA repeat units on the bacterial artificial chromosome illustrated that each fiber had at least five continuously moniliform hybridization signal points.This study provided a new candidate molecular marker for detecting intraspecific polymorphisms of S.japonica.In addition,the successful fiber-FISH analysis of the 45S rDNA on BAC molecule would contribute to the construction of the physical map and map-based cloning of this kelp.展开更多
The karyotype analysis and physical locations of 45S rDNA were carried out by means of fluorescence in situ hybridization in three species,and two forms of Sophora,two species of Robina,and one species of Amorpha.S.ja...The karyotype analysis and physical locations of 45S rDNA were carried out by means of fluorescence in situ hybridization in three species,and two forms of Sophora,two species of Robina,and one species of Amorpha.S.japonica L.,S.japonica L.f.oligophylla Franch.,S.japonica L.f.pendula Loud.,and S.xanthantha C.Y.Ma.are all tetraploids with 2n=28.There were four 45S rDNA sites in pericentromeric regions of two pairs of chromosomes in each of them.S.rubriflora Tsoong.is a triploid with 2n=21,and three sites were located in each satellite of group 5 chromosomes.In R.pseudoacacia L.(2n=2x=22),we examined four intensive signals in te-lomeric regions of two pairs of satellite chromosomes.In R.hispida L.(2n=2x=30),there were four other signals in centromeric regions besides those like in R.pseudoacacia.Amorpha fruticosa L.has most chromosomes(2n=40)among the eight materials,however,there were only six 45S rDNA loci and they laid in centromeric regions,and satellites of three pairs of chromosomes.45S rDNA is a valuable chromosomal landmark in karyotype analysis.The distribution and genomic organization of rDNA in the three genera were also discussed.展开更多
The genomic structures of Oryza sativa （A genome） and O. meyeriana （G genome） were comparatively studied using bicolor genomic in situ hybridization （GISH）. GISH was clearly able to discriminate between the chro...The genomic structures of Oryza sativa （A genome） and O. meyeriana （G genome） were comparatively studied using bicolor genomic in situ hybridization （GISH）. GISH was clearly able to discriminate between the chromosomes of O. sativa and O. meyeriana in the interspecific F1 hybrids without blocking DNA, and co-hybridization was hardly detected. The average mitotic chromosome length of O. meyeriana was found to be 1.69 times that of O. sativa. A comparison of 4,6-diamidino-2-phenylindole staining showed that the chromosomes of O. meyeriana were more extensively labelled, suggesting that the G genome is amplified with more repetitive sequences than the A genome. In interphase nuclei, 9-12 chromocenters were normally detected and nearly all the chromocenters constituted the G genome-specific DNA. More and larger chromocenters formed by chromatin compaction corresponding to the G genome were detected in the hybrid compared with its parents. During pachytene of the F1 hybrid, most chromosomes of A and G did not synapse each other except for 1-2 chromosomes paired at the end of their arms. At meiotic metaphase I, three types of chromosomal associations, i.e.O, sativa-O, sativa （A-A）, O. sativa-O, meyeriana （A-G） and O. meyeriana-O, meyeriana （G-G）, were observed in the F1 hybrid. The A-G chromosome pairing configurations included bivalents and trivalents. The results provided a foundation toward studying genome organization and evolution of O. meyeriana.展开更多
基金supported by the Key Technologies R&D Program of Hubei Province,China (2006AA201B17)
文摘The physical location of 45S and 5S rDNA sites by double-target fluorescence in situ hybridization （FISH） and 5S rDNA non-transcribed spacer （NTS） sequences was studied in five accessions of Nelumbo nucifera Gaertn.and one accession of N.nucifera subsp.lutea （Willd.）.The chromosome number of all tested materials was 2n=16.The loci of 5S rDNA were close to the centromere regions of chromosome 3,and the loci of 45S rDNA were found on chromosomes 7 and 8 in all the six tested accessions,respectively.Similarly,45S rDNAs were also located on chromosome 4 in four tested accessions.The 5S rRNA gene sequences were conserved and the NTS sequences were variable among the samples.N.nucifera subsp.lutea was the longest branch in the phylogenetic tree and clustered with N.nucifera cv.Liangzihu.N.nucifera cv.Heilongjiang and N.nucifera cv.Weishanhu showed a close relationship with each other.N.nucifera cv.Dahe Lian was closer to N.nucifera cv.Nihelu Lian than to other tested accessions.Analysis of the molecular karyotype and the 5S rRNA gene spacer sequence suggested the genetic diversity was limited within Nelumbo species and it seems suitable that American lotus was considered as the subspecies of N.nucifera.
基金supported by the National Natural Science Foundation of China(Grant No.41376136,32172963 to Z-G Z)the National Key R&D Program of China(Grant No.2018YFD0901500 to Y-H B)the World Class Discipline Project of Aquaculture(to Z-G Z).
文摘IGS is abundant in polymorphism,which is widely used in the analysis of intraspecific genetic diversity and phylogenetic relationships among geographical populations.In this study,the 45S rDNA repeat unit of Saccharina japonica was obtained for the first time by BAC clone sequencing.The total length of the 45S rDNA repeat unit of S.japonica was 8995 bp,including 5420 bp of 18S-5.8S-25S rDNA,and 3575 bp of IGS(Intergenic Spacer),with the GC content of 51.4%.The IGS was composed of a 465 bp of 3′-outer transcribed spacer(ETS),an 874 bp 5′-ETS,and a 2236 bp non-transcribed spacer(NTS),with the GC content of 50.1%.Fiber-FISH(fiber-fluorescence in situ hybridization)analysis of the distribution of 45S rDNA repeat units on the bacterial artificial chromosome illustrated that each fiber had at least five continuously moniliform hybridization signal points.This study provided a new candidate molecular marker for detecting intraspecific polymorphisms of S.japonica.In addition,the successful fiber-FISH analysis of the 45S rDNA on BAC molecule would contribute to the construction of the physical map and map-based cloning of this kelp.
文摘The karyotype analysis and physical locations of 45S rDNA were carried out by means of fluorescence in situ hybridization in three species,and two forms of Sophora,two species of Robina,and one species of Amorpha.S.japonica L.,S.japonica L.f.oligophylla Franch.,S.japonica L.f.pendula Loud.,and S.xanthantha C.Y.Ma.are all tetraploids with 2n=28.There were four 45S rDNA sites in pericentromeric regions of two pairs of chromosomes in each of them.S.rubriflora Tsoong.is a triploid with 2n=21,and three sites were located in each satellite of group 5 chromosomes.In R.pseudoacacia L.(2n=2x=22),we examined four intensive signals in te-lomeric regions of two pairs of satellite chromosomes.In R.hispida L.(2n=2x=30),there were four other signals in centromeric regions besides those like in R.pseudoacacia.Amorpha fruticosa L.has most chromosomes(2n=40)among the eight materials,however,there were only six 45S rDNA loci and they laid in centromeric regions,and satellites of three pairs of chromosomes.45S rDNA is a valuable chromosomal landmark in karyotype analysis.The distribution and genomic organization of rDNA in the three genera were also discussed.
文摘The genomic structures of Oryza sativa （A genome） and O. meyeriana （G genome） were comparatively studied using bicolor genomic in situ hybridization （GISH）. GISH was clearly able to discriminate between the chromosomes of O. sativa and O. meyeriana in the interspecific F1 hybrids without blocking DNA, and co-hybridization was hardly detected. The average mitotic chromosome length of O. meyeriana was found to be 1.69 times that of O. sativa. A comparison of 4,6-diamidino-2-phenylindole staining showed that the chromosomes of O. meyeriana were more extensively labelled, suggesting that the G genome is amplified with more repetitive sequences than the A genome. In interphase nuclei, 9-12 chromocenters were normally detected and nearly all the chromocenters constituted the G genome-specific DNA. More and larger chromocenters formed by chromatin compaction corresponding to the G genome were detected in the hybrid compared with its parents. During pachytene of the F1 hybrid, most chromosomes of A and G did not synapse each other except for 1-2 chromosomes paired at the end of their arms. At meiotic metaphase I, three types of chromosomal associations, i.e.O, sativa-O, sativa （A-A）, O. sativa-O, meyeriana （A-G） and O. meyeriana-O, meyeriana （G-G）, were observed in the F1 hybrid. The A-G chromosome pairing configurations included bivalents and trivalents. The results provided a foundation toward studying genome organization and evolution of O. meyeriana.
