RESUMO
Members in the YABBY gene family of proteins are plant-specific transcription factors that play critical roles in determining organ polarity. We have isolated a cDNA clone from rice that encodes a YABBY protein. This protein, OsYAB1, is similar to Arabidopsis YAB2 (50.3%) and YAB5 (47.6%). It carries a zinc-finger motif and a YABBY domain, as do those in Arabidopsis . A fusion protein between OsYAB1 and GFP is located in the nucleus. RNA gel-blot analysis showed that the OsYAB1 gene is preferentially expressed in flowers. In-situ hybridization experiments also indicated that the transcript accumulated in the stamen and carpel primordia. Unlike the Arabidopsis YABBY genes, however, the OsYAB1 gene does not show polar expression pattern in the tissues of floral organs. Our transgenic plants that ectopically expressed OsYAB1 were normal during the vegetative growth period, but then showed abnormalities in their floral structures. Spikelets contained supernumerary stamens and carpels compared with those of the wild types. These results suggest that OsYAB1 plays a major role in meristem development and maintenance of stamens and carpels, rather than in determining polarity.
Assuntos
Flores/genética , Oryza/genética , Proteínas de Plantas/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Núcleo Celular/metabolismo , Clonagem Molecular , DNA Complementar/genética , Flores/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Hibridização In Situ , Microscopia de Fluorescência , Dados de Sequência Molecular , Oryza/crescimento & desenvolvimento , Filogenia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , RNA de Plantas/genética , RNA de Plantas/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Homologia de Sequência de Aminoácidos , Fatores de Transcrição/metabolismoRESUMO
We have developed a binary T-DNA vector, pGA2717, that contains the promoter-less beta-glucuronidase (gus) gene adjacent to the right border and the promoter-less green fluorescence protein (gfp) gene next to the left border of the T-DNA. Therefore, inserting T-DNA into a gene can result in the activation of either gus or gfp. A total of 12 169 T-DNA insertional lines of japonica rice were generated using this binary vector. Out of 3140 lines examined, 0.5% of their mature seeds and 2.0% of the 3-day-old etiolated seedlings were GFP-positive. However, GUS assays of the same materials resulted in the identification of 151 (4.8%) GUS-positive lines. Using DNA gel blot and reverse transcription (RT)-PCR analyses, we confirmed that the GFP-positive lines were a true indication of gene trapping. A fusion transcript was also obtained between gfp and the trapped gene. We isolated 990 genomic sequences flanking T-DNA from our analysis of 2099 transgenic plants. Among the insertions, 625 T-DNAs were integrated into genic regions; 361 were located in intergenic regions. These tagging lines will be valuable in trapping and studying various genes for their expression patterns, as well as providing a useful tool for genetic approaches.
Assuntos
DNA Bacteriano/genética , Bases de Dados de Ácidos Nucleicos , Vetores Genéticos/genética , Sequência de Bases , Sítios de Ligação/genética , Técnicas de Cultura , DNA de Plantas/química , DNA de Plantas/genética , DNA de Plantas/isolamento & purificação , Expressão Gênica , Genes de Plantas/genética , Proteínas de Fluorescência Verde , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Dados de Sequência Molecular , Mutagênese Insercional , Oryza/genética , Plantas Geneticamente Modificadas , Plasmídeos/genética , Reação em Cadeia da Polimerase , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Análise de Sequência de DNA , Transcrição GênicaRESUMO
We analyzed 6749 lines tagged by the gene trap vector pGA2707. This resulted in the isolation of 3793 genomic sequences flanking the T-DNA. Among the insertions, 1846 T-DNAs were integrated into genic regions, and 1864 were located in intergenic regions. Frequencies were also higher at the beginning and end of the coding regions and upstream near the ATG start codon. The overall GC content at the insertion sites was close to that measured from the entire rice (Oryza sativa) genome. Functional classification of these 1846 tagged genes showed a distribution similar to that observed for all the genes in the rice chromosomes. This indicates that T-DNA insertion is not biased toward a particular class of genes. There were 764, 327, and 346 T-DNA insertions in chromosomes 1, 4 and 10, respectively. Insertions were not evenly distributed; frequencies were higher at the ends of the chromosomes and lower near the centromere. At certain sites, the frequency was higher than in the surrounding regions. This sequence database will be valuable in identifying knockout mutants for elucidating gene function in rice. This resource is available to the scientific community at http://www.postech.ac.kr/life/pfg/risd.
Assuntos
DNA Bacteriano/genética , DNA de Cadeia Simples/genética , Oryza/genética , Sequência de Bases , Primers do DNA , DNA Bacteriano/química , Éxons , Vetores Genéticos , Íntrons , Mutagênese Insercional , Plantas Geneticamente Modificadas/genética , Reação em Cadeia da Polimerase , Sitios de Sequências RotuladasRESUMO
We have previously generated a large pool of T-DNA insertional lines in rice. In this study, we screened those T-DNA pools for rice mutants that had defective chlorophylls. Among the 1,995 lines examined in the T2 generation, 189 showed a chlorophyll-deficient phenotype that segregated as a single recessive locus. Among the mutants, 10 lines were beta-glucuronidase (GUS)-positive in the leaves. Line 9-07117 has a T-DNA insertion into the gene that is highly homologous to XANTHA-F in barley and CHLH in Arabidopsis: This OsCHLH gene encodes the largest subunit of the rice Mg-chelatase, a key enzyme in the chlorophyll branch of the tetrapyrrole biosynthetic pathway. In the T2 and T3 generations, the chlorina mutant phenotypes are co-segregated with the T-DNA. We have identified two additional chlorina mutants that have a Tos17 insertion in the OsCHLH gene. Those phenotypes were co-segregated with Tos17 in the progeny. GUS assays and RNA blot analysis showed that expression of the OsCHLH gene is light inducible, while TEM analysis revealed that the thylakoid membrane of the mutant chloroplasts is underdeveloped. The chlorophyll content was very low in the OschlH mutants. This is the first report that T-DNA insertional mutagenesis can be used for functional analysis of rice genes.