RESUMO
The model plant Arabidopsis thaliana has five double-stranded RNA-binding proteins (DRB1-DRB5), two of which, DRB1 and DRB4, are well characterized. In contrast, the functions of DRB2, DRB3 and DRB5 have yet to be elucidated. In this study, we tried to uncover their functions using drb mutants and DRB-over-expressed lines. In over-expressed lines of all five DRB genes, the over-expression of DRB2 or DRB3 (DRB2ox or DRB3ox) conferred a downward-curled leaf phenotype, but the expression profiles of ten small RNAs were similar to that of the wild-type (WT) plant. Phenotypes were examined in response to abiotic stresses. Both DRB2ox and DRB3ox plants exhibited salt-tolerance. When these plants were exposed to cold stress, drb2 and drb3 over-accumulated anthocyanin but DRB2ox and DRB3ox did not. Therefore, the over-expression of DRB2 or DRB3 had pleiotropic effects on host plants. Microarray and deep-sequencing analyses indicated that several genes encoding key enzymes for anthocyanin biosynthesis, including chalcone synthase (CHS), dihydroflavonol reductase (DFR) and anthocyanidin synthase (ANS), were down-regulated in DRB3ox plants. When DRB3ox was crossed with the pap1-D line, which is an activation-tagged transgenic line that over-expresses the key transcription factor PAP1 (Production of anthocyanin pigmentation1) for anthocyanin biosynthesis, over-expression of DRB3 suppressed the expression of PAP1, CHS, DFR and ANS genes. DRB3 negatively regulates anthocyanin biosynthesis by modulating the level of PAP1 transcript. Since two different small RNAs regulate PAP1 gene expression, a possible function of DRB3 for small RNA biogenesis is discussed.
Assuntos
Antocianinas/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , RNA de Cadeia Dupla/metabolismo , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição/genética , Antocianinas/análise , Arabidopsis/fisiologia , Temperatura Baixa , Expressão Gênica , Perfilação da Expressão Gênica , Genótipo , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas Associadas a Pancreatite , Fenótipo , Folhas de Planta/genética , Folhas de Planta/fisiologia , RNA de Cadeia Dupla/genética , Proteínas de Ligação a RNA/genética , Tolerância ao Sal , Análise de Sequência de DNA , Estresse FisiológicoRESUMO
An inclusion complex consisting of a boronic acid fluorophore (C1-APB) and ß-cyclodextrin (ß-CyD) acts as a supramolecular sugar sensor whose response mechanism is based on photoinduced electron transfer (PET) from the excited pyrene to the boronic acid. We have investigated the PET process in C1-APB/CyD complexes by using time-resolved photoluminescence (TRPL) measurements at room temperature, and have succeeded in estimating the electron-transfer time to be about 1 ns. We have also studied the effects of CyDs on the PET process by comparing two kinds of CyDs (α-CyD, ß-CyD) under different water-dimethyisulfoxide (DMSO) concentration conditions. We found that the CyDs interacting with the boronic acid moiety completely inhibits PET quenching and increases the monomer fluorescence intensity.