Transcriptional profile of Pseudomonas syringae pv. phaseolicola NPS3121 in response to tissue extracts from a susceptible Phaseolus vulgaris L. cultivar.
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.


CONCLUSIONS
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.
Hernández-Morales
Alejandro
A
Departamento de Ingeniería Genética, Cinvestav-IPN Unidad Irapuato, Apdo Postal 629, CP 36821, Irapuato, Gto, México. aldolasa@yahoo.com.mx
De la Torre-Zavala
Susana
S
Ibarra-Laclette
Enrique
E
Hernández-Flores
José Luis
JL
Jofre-Garfias
Alba Estela
AE
Martínez-Antonio
Agustino
A
Alvarez-Morales
Ariel
A
D016000:Cluster Analysis; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D015698:Genomic Library; D007501:Iron / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009952:Ornithine / Q000031:analogs & derivatives / Q000378:metabolism; D027805:Phaseolus / Q000737:chemistry* / Q000382:microbiology; D010936:Plant Extracts / Q000737:chemistry; D044224:Pseudomonas syringae / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D014774:Virulence
D003470:Culture Media; D004269:DNA, Bacterial; D010936:Plant Extracts; C021234:phaseolotoxin; D007501:Iron; D009952:Ornithine