RESUMO
Genes that encode products containing a NAC domain, such as NO APICAL MERISTEM (NAM) in petunia, CUP-SHAPED COTYLEDON2 (CUC2) and NAP in Arabidopsis thaliana, have crucial functions in plant development. We describe here molecular aspects of the OsNAC genes that encode proteins with NAC domains in rice (Oryza sativa L.). Sequence analysis revealed that the NAC genes in plants can be divided into several subfamilies, such as the NAM, ATAF, and OsNAC3 subfamilies. In rice, OsNAC1 and OsNAC2 are classified in the NAM subfamily, which includes NAM and CUC2, while OsNAC5 and OsNAC6 fall into the ATAF subfamily. In addition to the members of these subfamilies, the rice genome contains the NAC genes OsNAC3, OsNAC4 (both in the OsNAC3 subfamily), OsNAC7, and OsNAC8. These results and Southern analysis indicate that the OsNAC genes constitute a large gene family in the rice genome. Each OsNAC gene is expressed in a specific pattern in different organs, suggesting that this family has diverse and important roles in rice development.
Assuntos
Genes de Plantas , Família Multigênica , Oryza/genética , Sequência de Aminoácidos , Sequência de Bases , Primers do DNA/genética , Expressão Gênica , Dados de Sequência Molecular , Especificidade de Órgãos , Homologia de Sequência de AminoácidosRESUMO
Myo-inositol-1-phosphate (I[1]P) synthase (EC 5.5.1.4) catalyzes the reaction from glucose 6-phosphate to I(1)P, the first step of myo-inositol biosynthesis. Among the metabolites of I(1)P is inositol hexakisphosphate, which forms a mixed salt called phytin or phytate, a storage form of phosphate and cations in seeds. We have isolated a rice (Oryza sativa L.) cDNA clone, pRINO1, that is highly homologous to the I(1)P synthase from yeast and plants. Northern analysis of total RNA showed that the transcript accumulated to high levels in embryos but was undetectable in shoots, roots, and flowers. In situ hybridization of developing seeds showed that the transcript first appeared in the apical region of globular-stage embryos 2 d after anthesis (DAA). Strong signals were detected in the scutellum and aleurone layer after 4 DAA. The level of the transcript in these cells increased until 7 DAA, after which time it gradually decreased. Phytin-containing particles called globoids appeared 4 DAA in the scutellum and aleurone layer, coinciding with the localization of the RINO1 transcript. The temporal and spatial patterns of accumulation of the RINO1 transcript and globoids suggest that I(1)P synthase directs phytin biosynthesis in rice seeds.
Assuntos
Mio-Inositol-1-Fosfato Sintase/genética , Oryza/genética , Oryza/metabolismo , Ácido Fítico/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Primers do DNA/genética , DNA Complementar/genética , DNA de Plantas/genética , Genes de Plantas , Hibridização In Situ , Dados de Sequência Molecular , Oryza/crescimento & desenvolvimento , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Plantas/genética , RNA de Plantas/metabolismo , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Homologia de Sequência de Aminoácidos , Transcrição GênicaRESUMO
We identified the sites for the initiation of transcription of a gene for subunit 1 of F1-ATPase (atp1) in rice mitochondrial DNA. Capping and ribonuclease protection experiments in vitro, together with primer extension analysis, demonstrated that there were at least eight transcription initiation sites upstream of atp1. One initiation site, expressed most actively, was flanked by a sequence identical to the consensus promotor motif of rice mitochondrial genes. However, the sequences surrounding the other seven initiation sites exhibited no similarity to the consensus sequence.
Assuntos
Genes de Plantas , Mitocôndrias/genética , Oryza/genética , ATPases Translocadoras de Prótons/genética , Transcrição Gênica , Sequência de Bases , Southern Blotting , Sequência Consenso , Enzimas de Restrição do DNA/metabolismo , Mitocôndrias/enzimologia , Dados de Sequência Molecular , Oryza/enzimologia , Regiões Promotoras Genéticas , Capuzes de RNA , RNA Mensageiro/genética , RNA de Plantas/genéticaRESUMO
A simple method for differential screening of randomly amplified cDNAs using primers for detection of randomly amplified polymorphic DNA (RAPD) has been developed. To detect and clone differentially expressed genes during regeneration, we compared mRNAs from rice calli before the induction of regeneration, 7 days after induction of organogenesis, and 7 days after induction of embryogenesis. The cDNAs were amplified by the polymerase chain reaction (PCR) with a single RAPD primer and were separated by agarose gel electrophoresis. A number of differentially amplified bands were detected. Five of the specific bands were cloned and their expression was analyzed by Northern hybridization. We isolated a cDNA clone which is specific to organogenesis, two clones which are specific to embryogenesis, and two clones which are common to organogenesis and embryogenesis but not present in unorganized calli. Two of the isolated clones are expressed at low levels. Thus, this method is useful for cloning of differentially expressed genes whose transcripts are of low abundance. Expression of one of the embryogenesis-specific cDNA clones, pCRE2, was analyzed in detail. The pCRE2 transcript accumulates transiently in calli after the induction of embryogenesis, and its accumulation in planta was specific to zygotic embryos.
