RESUMO
Xylella fastidiosa inhabits the plant xylem, a nutrient-poor environment, so that mechanisms to sense and respond to adverse environmental conditions are extremely important for bacterial survival in the plant host. Although the complete genome sequences of different Xylella strains have been determined, little is known about stress responses and gene regulation in these organisms. In this work, a DNA microarray was constructed containing 2,600 ORFs identified in the genome sequencing project of Xylella fastidiosa 9a5c strain, and used to check global gene expression differences in the bacteria when it is infecting a symptomatic and a tolerant citrus tree. Different patterns of expression were found in each variety, suggesting that bacteria are responding differentially according to each plant xylem environment. The global gene expression profile was determined and several genes related to bacterial survival in stressed conditions were found to be differentially expressed between varieties, suggesting the involvement of different strategies for adaptation to the environment. The expression pattern of some genes related to the heat shock response, toxin and detoxification processes, adaptation to atypical conditions, repair systems as well as some regulatory genes are discussed in this paper. DNA microarray proved to be a powerful technique for global transcriptome analyses. This is one of the first studies of Xylella fastidiosa gene expression in vivo which helped to increase insight into stress responses and possible bacterial survival mechanisms in the nutrient-poor environment of xylem vessels.
Assuntos
Citrus/microbiologia , Expressão Gênica , Análise de Sequência com Séries de Oligonucleotídeos , Xylella/crescimento & desenvolvimento , Xylella/genética , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
The obtainment of transgenic edible plants carrying recombinant antigens is a desired issue in search for economic alternatives viewing vaccine production. Here we report a strategy for genetic transformation of lettuce plants (Lactuca sativa L.) using the surface antigen HBsAg of hepatitis B virus. Transgenic lettuce seedlings were obtained through the application of a regulated balance of plant growth regulators. Genetic transformation process was acquired by cocultivation of cotyledons with Agrobacterium tumefaciens harboring the recombinant plasmid. It is the first description of a lettuce Brazilian variety "Vitória de Verão" genetically modified.
Assuntos
Antígenos de Superfície da Hepatite B/genética , Vacinas contra Hepatite B/genética , Lactuca/genética , Plantas Geneticamente Modificadas/genética , DNA Recombinante , Lactuca/imunologia , Reguladores de Crescimento de Plantas , Plantas Geneticamente Modificadas/imunologia , Plântula/genética , Plântula/imunologia , Vacinas de Plantas ComestíveisRESUMO
Assimilation of nitrate and ammonium are vital procedures for plant development and growth. From these primary paths of inorganic nitrogen assimilation, this metabolism integrates diverse paths for biosynthesis of macromolecules, such as amino acids and nucleotides, and the central intermediate metabolism, like carbon metabolism and photorespiration. This paper reports research performed in the CitEST (Citrus Expressed Sequence Tag) database for the main genes involved in nitrogen metabolism and those previously described in other organisms. The results show that a complete cluster of genes involved in the assimilation of nitrogen and the metabolisms of glutamine, glutamate, aspartate and asparagine can be found in the CitEST data. The main enzymes found were nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthetase (GOGAT), glutamate dehydrogenase (GDH), aspartate aminotransferase (AspAT) and asparagine synthetase (AS). The different enzymes involved in this metabolism have been shown to be highly conserved among the Citrus and Poncirus species. This work serves as a guide for future functional analysis of these enzymes in citrus.