RESUMO
BACKGROUND: Pseudomonas syringae pv. phaseolicola is a Gram-negative plant-pathogenic bacterium that causes "halo blight" disease of beans (Phaseolus vulgaris L.). This disease affects both foliage and pods, and is a major problem in temperate areas of the world. Although several bacterial genes have been determined as participants in pathogenesis, the overall process still remains poorly understood, mainly because the identity and function of many of the genes are largely unknown. In this work, a genomic library of P. syringae pv. phaseolicola NPS3121 was constructed and PCR amplification of individual fragments was carried out in order to print a DNA microarray. This microarray was used to identify genes that are differentially expressed when bean leaf extracts, pod extracts or apoplastic fluid were added to the growth medium. RESULTS: Transcription profiles show that 224 genes were differentially expressed, the majority under the effect of bean leaf extract and apoplastic fluid. Some of the induced genes were previously known to be involved in the first stages of the bacterial-plant interaction and virulence. These include genes encoding type III secretion system proteins and genes involved in cell-wall degradation, phaseolotoxin synthesis and aerobic metabolism. On the other hand, most repressed genes were found to be involved in the uptake and metabolism of iron. CONCLUSION: This study furthers the understanding of the mechanisms involved, responses and the metabolic adaptation that occurs during the interaction of P. syringae pv. phaseolicola with a susceptible host plant.
Assuntos
Perfilação da Expressão Gênica , Phaseolus/química , Pseudomonas syringae/genética , Análise por Conglomerados , Meios de Cultura , DNA Bacteriano/genética , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Biblioteca Genômica , Ferro/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Ornitina/análogos & derivados , Ornitina/metabolismo , Phaseolus/microbiologia , Extratos Vegetais/química , Pseudomonas syringae/metabolismo , Pseudomonas syringae/patogenicidade , VirulênciaRESUMO
Callus and cell suspension can be used for long-term cell cultures maintenance. This chapter describes procedures for the induction of somatic embryos of garlic, keeping a regeneration capacity for more than 5 yr, as well as the maintenance of a tobacco suspension culture (NT-1 cells), for more than 10 yr. Methods for plant regeneration and growth kinetics of garlic cultures are described, as well as for cell viability of NT-1 cells stained with 2,3,5 triphenyltetrazolium chloride. The packed cell volume determination as a parameter of growth is detailed.