RESUMO
The subfamily of the Lemnoideae belongs to a different order than other monocotyledonous species that have been sequenced and comprises aquatic plants that grow rapidly on the water surface. Here we select Spirodela polyrhiza for whole-genome sequencing. We show that Spirodela has a genome with no signs of recent retrotranspositions but signatures of two ancient whole-genome duplications, possibly 95 million years ago (mya), older than those in Arabidopsis and rice. Its genome has only 19,623 predicted protein-coding genes, which is 28% less than the dicotyledonous Arabidopsis thaliana and 50% less than monocotyledonous rice. We propose that at least in part, the neotenous reduction of these aquatic plants is based on readjusted copy numbers of promoters and repressors of the juvenile-to-adult transition. The Spirodela genome, along with its unique biology and physiology, will stimulate new insights into environmental adaptation, ecology, evolution and plant development, and will be instrumental for future bioenergy applications.
Assuntos
Araceae/crescimento & desenvolvimento , Araceae/genética , Genoma de Planta/genética , Água Doce , Dados de Sequência MolecularRESUMO
The DIURNAL project ( http://diurnal.cgrb.oregonstate.edu/ ) provides a graphical interface for mining and viewing diurnal and circadian microarray data for Arabidopsis thaliana, poplar, and rice. The database is searchable and provides access to several user-friendly Web-based data-mining tools with easy-to-understand output. The associated tools include HAYSTACK ( http://haystack.cgrb.oregonstate.edu/ ) and ELEMENT ( http://element.cgrb.oregonstate.edu/ ). HAYSTACK is a model-based pattern-matching algorithm for identifying genes that are coexpressed and potentially coregulated. HAYSTACK can be used to analyze virtually any large-scale microarray data set and provides an alternative method for clustering microarray data from any experimental system by grouping together genes whose expression patterns match the same or similar user-defined patterns. ELEMENT is a Web-based program for identifying potential cis-regulatory elements in the promoters of coregulated genes in Arabidopsis, poplar, and rice. Together, DIURNAL, HAYSTACK, and ELEMENT can be used to facilitate cross-species comparisons among the plant species supported and to accelerate functional genomics efforts in the laboratory.
Assuntos
Ritmo Circadiano/genética , Bases de Dados Genéticas , Plantas/genética , Algoritmos , Arabidopsis/genética , Arabidopsis/fisiologia , Ritmo Circadiano/fisiologia , DNA de Plantas/genética , Perfilação da Expressão Gênica/estatística & dados numéricos , Genes de Plantas , Modelos Genéticos , Análise de Sequência com Séries de Oligonucleotídeos/estatística & dados numéricos , Oryza/genética , Oryza/fisiologia , Reconhecimento Automatizado de Padrão , Fenômenos Fisiológicos Vegetais , Populus/genética , Populus/fisiologia , Regiões Promotoras Genéticas , Elementos Reguladores de Transcrição , SoftwareRESUMO
The Arabidopsis photoreceptors cry1, cry2 and phyB are known to play roles in the regulation of flowering time, for which the molecular mechanisms remain unclear. We have previously hypothesized that phyB mediates a red-light inhibition of floral initiation and cry2 mediates a blue-light inhibition of the phyB function. Studies of the cry2/phyB double mutant provide direct evidence in support of this hypothesis. The function of cryptochromes in floral induction was further investigated using the cry2/cry1 double mutants. The cry2/cry1 double mutants showed delayed flowering in monochromatic blue light, whereas neither monogenic cry1 nor cry2 mutant exhibited late flowering in blue light. This result suggests that, in addition to the phyB-dependent function, cry2 also acts redundantly with cry1 to promote floral initiation in a phyB-independent manner. To understand how photoreceptors regulate the transition from vegetative growth to reproductive development, we examined the effect of sequential illumination by blue light and red light on the flowering time of plants. We found that there was a light-quality-sensitive phase of plant development, during which the quality of light exerts a profound influence on flowering time. After this developmental stage, which is between approximately day-1 to day-7 post germination, plants are committed to floral initiation and the quality of light has little effect on the flowering time. Mutations in either the PHYB gene or both the CRY1 and CRY2 genes resulted in the loss of the light-quality-sensitive phase manifested during floral development. The commitment time of floral transition, defined by a plant's sensitivity to light quality, coincides with the commitment time of inflorescence development revealed previously by a plant's sensitivity to light quantity - the photoperiod. Therefore, the developmental mechanism resulting in the commitment to flowering appears to be the direct target of the antagonistic actions of the photoreceptors.
Assuntos
Arabidopsis/fisiologia , Proteínas de Drosophila , Proteínas do Olho , Flavoproteínas/fisiologia , Células Fotorreceptoras de Invertebrados , Células Fotorreceptoras , Complexo de Proteínas do Centro de Reação Fotossintética , Fitocromo/fisiologia , Fatores de Transcrição , Arabidopsis/genética , Proteínas de Arabidopsis , Criptocromos , Flavoproteínas/genética , Luz , Mutagênese , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Fitocromo/genética , Fitocromo B , Receptores Acoplados a Proteínas GRESUMO
The shift in plants from vegetative growth to floral development is regulated by red-far-red light receptors (phytochromes) and blue-ultraviolet A light receptors (cryptochromes). A mutation in the Arabidopsis thaliana CRY2 gene encoding a blue-light receptor apoprotein (CRY2) is allelic to the late-flowering mutant, fha. Flowering in cry2/fha mutant plants is only incompletely responsive to photoperiod. Cryptochrome 2 (cry2) is a positive regulator of the flowering-time gene CO, the expression of which is regulated by photoperiod. Analysis of flowering in cry2 and phyB mutants in response to different wavelengths of light indicated that flowering is regulated by the antagonistic actions of phyB and cry2.
Assuntos
Proteínas de Arabidopsis , Arabidopsis/fisiologia , Proteínas de Drosophila , Proteínas do Olho , Flavoproteínas/fisiologia , Luz , Células Fotorreceptoras de Invertebrados , Células Fotorreceptoras , Proteínas de Plantas/fisiologia , Arabidopsis/genética , Mapeamento Cromossômico , Criptocromos , Proteínas de Ligação a DNA/genética , Flavoproteínas/genética , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Dados de Sequência Molecular , Mutação , Fotoperíodo , Fitocromo/genética , Fitocromo/fisiologia , Fitocromo A , Fitocromo B , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Plantas/genética , RNA de Plantas/metabolismo , Receptores Acoplados a Proteínas G , Fatores de Transcrição/genéticaRESUMO
The development of non-viral gene therapy has been hampered by an inability to reproducibly manufacture and characterize delivery system components and final formulations. Formation of interpolyelectrolyte complexes as the basis of various gene delivery methods has been approached as the first step towards development of synthetic viruses. We have found that preparation of interpolyelectrolyte complexes from disperse reagents gives a more homogeneous gene delivery vehicle than other methods. Methods which increase homogeneity also result in higher transfection efficiency in vivo. Expression levels of human growth hormone and other reporter proteins in mice confirm the potential of parenteral non-viral gene delivery for some therapeutic applications. Serum is demonstrated to inhibit transfection efficiency in vivo. Our results suggest that further development of methods to manufacture homogeneous disperse non-viral delivery vehicles with stealth characteristics may enhance both the potency and reproducibility of gene transfer in vivo.
