RESUMO
We reported previously that the rice (Oryza sativa L.) cleistogamous mutation superwoman1-cleistogamy1 (spw1-cls1) was applicable to inhibit outcrossing between genetically modified varieties and their relatives, which causes pollen-mediated gene flow or disturbance of line purity. The cleistogamy of spw1-cls1 is caused by decreased protein-protein interactions between the mutant SPW1 and its partner proteins. Importantly, these interactions are restored under low-temperature conditions, but whether the cleistogamy of spw1-cls1 is affected by this phenomenon was unclear. In this study, we cultivated spw1-cls1 in various regions of Japan and confirmed that its flowers opened at low temperatures. Moreover, we compared the morphology of a series of lodicules generated at various temperatures. The results indicated that the cleistogamy of spw1-cls1 is thermosensitive and is gradually disturbed as the temperature decreases. This was correlated with the protein interaction pattern of the mutant SPW1 as reported previously. Then, we revealed the critical period for the low-temperature-induced instability of the phenotype of spw1-cls1 and examined the effect of daily temperature changes on cleistogamy. The results may facilitate simulation of the phenotype of spw1-cls1 at various temperatures and the prediction of regions where the cleistogamy of spw1-cls1 can be stably used to inhibit outcrossing.
RESUMO
Outcrossing between cultivated plants and their related wild species may result in the loss of favourable agricultural traits in the progeny or escape of transgenes in the environment. Outcrossing can be physically prevented by using cleistogamous (i.e. closed-flower) plants. In rice, flower opening is dependent on the mechanical action of fleshy organs called lodicules, which are generally regarded as the grass petal equivalents. Lodicule identity and development are specified by the action of protein complexes involving the SPW1 and OsMADS2 transcription factors. In the superwoman1-cleistogamy1 (spw1-cls1) mutant, SPW1 is impaired for heterodimerization with OsMADS2 and consequently spw1-cls1 shows thin, ineffective lodicules. However, low temperatures help stabilise the mutated SPW1/OsMADS2 heterodimer and lodicule development is restored when spw1-cls1 is grown in a cold environment, resulting in the loss of the cleistogamous phenotype. To identify a novel, temperature-stable cleistogamous allele of SPW1, targeted and random mutations were introduced into the SPW1 sequence and their effects over SPW1/OsMADS2 dimer formation were assessed in yeast two-hybrid experiments. In parallel, a novel cleistogamous allele of SPW1 called spw1-cls2 was isolated from a forward genetic screen. In spw1-cls2, a mutation leading to a change of an amino acid involved in DNA binding by the transcription factor was identified. Fertility of spw1-cls2 is somewhat decreased under low temperatures but unlike for spw1-cls1, the cleistogamous phenotype is maintained, making the line a safer and valuable genetic resource for gene containment.
Assuntos
Flores/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/genética , Mutação , Oryza/genética , Alelos , Proteínas de Arabidopsis/genética , Flores/anatomia & histologia , Flores/citologia , Flores/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Genes de Plantas , Proteínas de Domínio MADS/metabolismo , Tamanho do Órgão , Oryza/anatomia & histologia , Oryza/crescimento & desenvolvimento , Fenótipo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Ligação Proteica , Homologia de Sequência de Aminoácidos , Temperatura , Fatores de Transcrição/genética , Transgenes , Técnicas do Sistema de Duplo-Híbrido , beta-Galactosidase/metabolismoRESUMO
Various vaccine therapies for Alzheimer's disease (AD) have been investigated. Here we report transgenic rice expressing amyloid ß-peptide (Aß). The Aß42 gene fused with a green fluorescent protein gene was introduced into rice using the Agrobacterium method. When transgenic brown rice expressing Aß was orally administered to mice, serum anti-Aß antibody titers were elevated. The same results were observed when mice were fed boiled, transgenic brown rice. The results indicate that an edible vaccine against AD using rice may be feasible. A vaccine derived from rice would be far cheaper than existing medical vaccines.
Assuntos
Doença de Alzheimer/imunologia , Peptídeos beta-Amiloides/uso terapêutico , Imunoterapia Ativa/métodos , Oryza/genética , Fragmentos de Peptídeos/uso terapêutico , Plantas Geneticamente Modificadas/metabolismo , Agrobacterium tumefaciens/genética , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/imunologia , Animais , Anticorpos/sangue , Ensaio de Imunoadsorção Enzimática , Camundongos , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/imunologia , Transformação Bacteriana , Vacinas de Plantas Comestíveis/uso terapêuticoRESUMO
The most chilling-sensitive stage of rice has been found to be at the onset of microspore release. The microsporocytes produce a wall of callose between the primary cell wall and the plasma membrane, and it has been shown that precise regulation of callose synthesis and degradation in anther is essential for fertile pollen formation. In this study, genes for 10 callose synthases in the rice genome were fully annotated and phylogenetically analyzed. Expression analysis of these genes showed that OsGSL5, an ortholog of microsporogenesis-related AtGSL2, was specifically expressed in anthers, and was notably downregulated by cooling treatment. Gene expression profiles of Rho-type small GTP-binding proteins in rice anther were also analyzed. The mechanisms of callose synthesis in rice pollen formation and its relationships with cool tolerance are discussed.
Assuntos
Regulação da Expressão Gênica de Plantas/genética , Glucosiltransferases/genética , Oryza/enzimologia , Oryza/genética , Proteínas rho de Ligação ao GTP/genética , Membrana Celular/enzimologia , DNA Mitocondrial/genética , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica/genética , Genoma de Planta/genética , Glucosiltransferases/metabolismo , Filogenia , RNA Mensageiro/genéticaRESUMO
Rice is most chilling sensitive at the onset of microspore release. Chilling treatment at this stage causes male sterility. The gene expression profile during the microspore development process under chilling stress was revealed using a microarray that included 8,987 rice cDNAs. As many as 160 cDNAs were up- or down-regulated by chilling during the microspore release stage. RT-PCR analysis of 5 genes confirmed the microarray results. We identified 3 novel genes whose expression levels were remarkably changed by chilling in rice anther. A new cis element that includes a DNA transposon Castaway sequence was found in the 5' upstream region of two genes which were conspicuously down-regulated by chilling temperatures in rice anther.
Assuntos
Temperatura Baixa , Regulação da Expressão Gênica de Plantas/fisiologia , Oryza/genética , Região 5'-Flanqueadora/genética , Sequência de Bases , Elementos de DNA Transponíveis , Elementos Facilitadores Genéticos , Flores/genética , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas de Plantas/genéticaRESUMO
Beta-1,3-glucanases are referred to as pathogenesis-related proteins and they are also involved in several developmental processes. We isolated a cDNA for beta-1,3-glucanase from rice anther and named it Oryza sativa glucanase 1 (Osg1). Phylogenetic analysis showed that Osg1 belonged to monocotyledonous endo-beta-1,3-glucanase subgroup A. RT-PCR analysis revealed that Osg1 transcripts were present in leaves, roots, and anthers.