The distribution of repetitive DNAs along chromosomes is one of the crucial elements for understanding the organization and the evolution of plant genomes. Using a modified genomic in situ hybridization （GISH） proce...The distribution of repetitive DNAs along chromosomes is one of the crucial elements for understanding the organization and the evolution of plant genomes. Using a modified genomic in situ hybridization （GISH） procedure, fluorescence in situ hybridization （FISH） with genomic DNA to their own chromosomes （called self-genomic in situ hybridization, self-GISH） was carried out in six selected plant species with different genome size and amount of repetitive DNA. Nonuniform distribution of the fluorescent labeled probe DNA was observed on the chromosomes of all the species that were tested. The signal patterns varied among species and were related to the genome size. The chromosomes of the small Arabidopsis genome were labeled almost only in the pericentromeric regions and the nucleolus organizer regions （NORs）. The signals in the relatively small genomes, rice, sorghum, and Brassica oleracea var. capitata L., were dispersed along the chromosome lengths, with a predominant distribution in the pericentromeric or proximal regions and some heterochromatic arms. All chromosomes of the large genomes, maize and barley, were densely labeled with strongly labeled regions and weakly labeled or unlabeled regions being arranged alternatively throughout the lengths. In addition, enhanced signal bands were shown in all pericentromeres and the NORs in B. oleracea var. capitata, and in all pericentromeric regions and certain intercalary sites in barley. The enhanced signal band pattern in barley was found consistent with the N-banding pattern of this species. The GISH with self-genomic DNA was compared with FISH with Cot-1 DNA in rice, and their signal patterns are found to be basically consistent. Our results showed that the self-GISH signals actually reflected the hybridization of genomic repetitive DNAs to the chromosomes, thus the self-GISH technique would be useful for revealing the distribution of the regions where repetitive DNAs concentrate along chromosomes and some chromatin differentiation associated with repetitive DNAs in plants.展开更多
Fabaceae is the third largest family of flowering plants and is unique among crops in their ability of fixing atmospheric nitrogen. Fabaceae is one of the few plant families with extensive genomic data available in mu...Fabaceae is the third largest family of flowering plants and is unique among crops in their ability of fixing atmospheric nitrogen. Fabaceae is one of the few plant families with extensive genomic data available in multiple species. The unprecedented complexity and impending completeness of these data create opportunities for discovering new approaches. The Legume and Medicago share much-conserved colinearity between their genomes which can be exploited for the genomic research in Leguminosae crops. In this study, 1,952,191 ESTs of 8 Leguminosae species were clustered into unigenes contigs and compared with Medicago truncatula gene indices. Almost all the unigenes of Leguminosae species showed high similarity with Medicago genes, except for those of Lens culinaris, where 95% of unigenes were found similar. A total of 10,874 SSRs were identified in the unigenes. Functional annotation of unigenes showed that the majority of the genes are present in metabolism and energy functional classes. It is expected that comparative genomic analysis between Medicago and related crop species will expedite research in other Legume species. This would be helpful for genomics as well as evolutionary studies, and the DNA markers developed can be used for mapping, tagging and cloning of specific important genes in Leguminosae.展开更多
基金This work was supported by the National Natural Sciences Foundation of China (No. 39870423).
文摘The distribution of repetitive DNAs along chromosomes is one of the crucial elements for understanding the organization and the evolution of plant genomes. Using a modified genomic in situ hybridization （GISH） procedure, fluorescence in situ hybridization （FISH） with genomic DNA to their own chromosomes （called self-genomic in situ hybridization, self-GISH） was carried out in six selected plant species with different genome size and amount of repetitive DNA. Nonuniform distribution of the fluorescent labeled probe DNA was observed on the chromosomes of all the species that were tested. The signal patterns varied among species and were related to the genome size. The chromosomes of the small Arabidopsis genome were labeled almost only in the pericentromeric regions and the nucleolus organizer regions （NORs）. The signals in the relatively small genomes, rice, sorghum, and Brassica oleracea var. capitata L., were dispersed along the chromosome lengths, with a predominant distribution in the pericentromeric or proximal regions and some heterochromatic arms. All chromosomes of the large genomes, maize and barley, were densely labeled with strongly labeled regions and weakly labeled or unlabeled regions being arranged alternatively throughout the lengths. In addition, enhanced signal bands were shown in all pericentromeres and the NORs in B. oleracea var. capitata, and in all pericentromeric regions and certain intercalary sites in barley. The enhanced signal band pattern in barley was found consistent with the N-banding pattern of this species. The GISH with self-genomic DNA was compared with FISH with Cot-1 DNA in rice, and their signal patterns are found to be basically consistent. Our results showed that the self-GISH signals actually reflected the hybridization of genomic repetitive DNAs to the chromosomes, thus the self-GISH technique would be useful for revealing the distribution of the regions where repetitive DNAs concentrate along chromosomes and some chromatin differentiation associated with repetitive DNAs in plants.
文摘Fabaceae is the third largest family of flowering plants and is unique among crops in their ability of fixing atmospheric nitrogen. Fabaceae is one of the few plant families with extensive genomic data available in multiple species. The unprecedented complexity and impending completeness of these data create opportunities for discovering new approaches. The Legume and Medicago share much-conserved colinearity between their genomes which can be exploited for the genomic research in Leguminosae crops. In this study, 1,952,191 ESTs of 8 Leguminosae species were clustered into unigenes contigs and compared with Medicago truncatula gene indices. Almost all the unigenes of Leguminosae species showed high similarity with Medicago genes, except for those of Lens culinaris, where 95% of unigenes were found similar. A total of 10,874 SSRs were identified in the unigenes. Functional annotation of unigenes showed that the majority of the genes are present in metabolism and energy functional classes. It is expected that comparative genomic analysis between Medicago and related crop species will expedite research in other Legume species. This would be helpful for genomics as well as evolutionary studies, and the DNA markers developed can be used for mapping, tagging and cloning of specific important genes in Leguminosae.
