RESUMO
The plant cell wall is an important factor for determining cell shape, function and response to the environment. Secondary cell walls, such as those found in xylem, are composed of cellulose, hemicelluloses and lignin and account for the bulk of plant biomass. The coordination between transcriptional regulation of synthesis for each polymer is complex and vital to cell function. A regulatory hierarchy of developmental switches has been proposed, although the full complement of regulators remains unknown. Here we present a protein-DNA network between Arabidopsis thaliana transcription factors and secondary cell wall metabolic genes with gene expression regulated by a series of feed-forward loops. This model allowed us to develop and validate new hypotheses about secondary wall gene regulation under abiotic stress. Distinct stresses are able to perturb targeted genes to potentially promote functional adaptation. These interactions will serve as a foundation for understanding the regulation of a complex, integral plant component.
Assuntos
Arabidopsis/genética , Arabidopsis/metabolismo , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Redes Reguladoras de Genes/genética , Fatores de Transcrição/metabolismo , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , DNA de Plantas/genética , DNA de Plantas/metabolismo , Fatores de Transcrição E2F/metabolismo , Retroalimentação , Regulação da Expressão Gênica no Desenvolvimento/genética , Deficiências de Ferro , Especificidade de Órgãos , Regiões Promotoras Genéticas/genética , Reprodutibilidade dos Testes , Salinidade , Fatores de Tempo , Xilema/genética , Xilema/crescimento & desenvolvimento , Xilema/metabolismoRESUMO
The expression of the Comamonas testosteroni gene, encoding 3beta/17beta-hydroxysteroid dehydrogenase enzyme (3beta/17beta-HSD), was analyzed at the transcriptional level. Northern blot analysis detected a 1 kb transcript in bacterial cells grown in minimum media supplemented with Casamino acids and testosterone. Also this transcript was observed when cells were grown in presence of 1-dehydrotestosterone, androstenedione and 1,4-androstadien-3, 17dione, but not in presence of acetate, citrate, cholic acid, cholesterol, and cortisol. In addition, this effect was dependent on the presence of another carbon source in the growth medium used, revealing catabolite repression.
