RESUMO
Carotenoids represent some of the most important secondary metabolites in the human diet, and tomato (Solanum lycopersicum) is a rich source of these health-promoting compounds. In this work, a novel and fruit-related regulator of pigment accumulation in tomato has been identified by artificial neural network inference analysis and its function validated in transgenic plants. A tomato fruit gene regulatory network was generated using artificial neural network inference analysis and transcription factor gene expression profiles derived from fruits sampled at various points during development and ripening. One of the transcription factor gene expression profiles with a sequence related to an Arabidopsis (Arabidopsis thaliana) ARABIDOPSIS PSEUDO RESPONSE REGULATOR2-LIKE gene (APRR2-Like) was up-regulated at the breaker stage in wild-type tomato fruits and, when overexpressed in transgenic lines, increased plastid number, area, and pigment content, enhancing the levels of chlorophyll in immature unripe fruits and carotenoids in red ripe fruits. Analysis of the transcriptome of transgenic lines overexpressing the tomato APPR2-Like gene revealed up-regulation of several ripening-related genes in the overexpression lines, providing a link between the expression of this tomato gene and the ripening process. A putative ortholog of the tomato APPR2-Like gene in sweet pepper (Capsicum annuum) was associated with pigment accumulation in fruit tissues. We conclude that the function of this gene is conserved across taxa and that it encodes a protein that has an important role in ripening.
Assuntos
Proteínas de Arabidopsis/química , Capsicum/genética , Frutas/genética , Genes de Plantas/genética , Redes Neurais de Computação , Pigmentos Biológicos/metabolismo , Solanum lycopersicum/genética , Carotenoides/metabolismo , Frutas/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes/genética , Solanum lycopersicum/crescimento & desenvolvimento , Fenótipo , Pigmentação/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Tocoferóis/metabolismo , Fatores de Transcrição/metabolismoRESUMO
In March 2005, U.S. authorities informed the European Commission of the inadvertent release of unauthorized maize GM event Bt10 in their market and subsequently the grain channel. In the United States measures were taken to eliminate Bt10 from seed and grain supplies; in the European Union an embargo for maize gluten and brewer's grain import was implemented unless certified of Bt10 absence with a Bt10-specific PCR detection method. With the aim of assessing the validity of the Bt10 detection method, an in-depth analysis of the molecular organization of the genetic modification of this event was carried out by both the company Syngenta, who produced the event, and the European Commission Joint Research Centre, who validated the detection method. Using a variety of molecular analytical tools, both organizations found the genetic modification of event Bt10 to be very complex in structure, with rearrangements, inversions, and multiple copies of the structural elements (cry1Ab, pat, and the amp gene), interspersed with small genomic maize fragments. Southern blot analyses demonstrated that all Bt10 elements were found tightly linked on one large fragment, including the region that would generate the event-specific PCR amplicon of the Bt10 detection method. This study proposes a hypothetical map of the insert of event Bt10 and concludes that the validated detection method for event Bt10 is fit for its purpose.
Assuntos
Proteínas de Bactérias/genética , DNA de Plantas/análise , DNA Recombinante/análise , Endotoxinas/genética , Proteínas Hemolisinas/genética , Plantas Geneticamente Modificadas/genética , Sementes/genética , Zea mays/genética , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/análise , Southern Blotting , Endotoxinas/análise , Europa (Continente) , Biblioteca Gênica , Proteínas Hemolisinas/análise , Legislação sobre Alimentos , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Estados UnidosRESUMO
To identify Arabidopsis mutants that constitutively express systemic acquired resistance (SAR), we constructed reporter lines expressing the firefly luciferase gene under the control of the SAR-inducible PR-1 promoter (PR-1/luc). After EMS mutagenesis of a well-characterized transgenic line, we screened 250,000 M(2) plants for constitutive expression of the reporter gene in vivo. From a mutant collection containing several hundred putative mutants, we concentrated on 16 mutants lacking spontaneous hypersensitive response (HR) cell death. We mapped 4 of these constitutive immunity (cim) mutants to chromosome arms. Constitutive expression of disease resistance was established by analyzing responses to virulent Peronospora parasitica and Pseudomonas syringae strains, by RNA blot analysis for endogenous marker genes, and by determination of salicylic acid levels in the mutants. The variety of the cim phenotypes allowed us to define distinct steps in both the canonical SAR signaling pathway and a separate pathway for resistance to Erysiphe cichoracearum, active in only a subset of the mutants.
