CIQUIBIC   05472
CENTRO DE INVESTIGACIONES EN QUIMICA BIOLOGICA DE CORDOBA
Unidad Ejecutora - UE
artículos
Título:
The Arabidopsis genome displays centromeric DNA hypomethylation and cytological alterations of heterochromatin upon the attack by virulent Pseudomonas
Autor/es:
PAVET V; QUINTERO C; CECCHINI N; ROSA AL; ALVAREZ ME
Revista:
MOLECULAR PLANT-MICROBE INTERACTIONS
Editorial:
American Phytopathological Society Press
Referencias:
Año: 2006 vol. 19 p. 577 - 587
ISSN:
0894-0282
Resumen:
Plant tissues display major alterations upon the perception
of microbial pathogens. Changes of cytoplasmic and apoplastic
components that sense and transduce plant defenses
have been extensively characterized. In contrast, less information
is available about modifications affecting the plant
nuclear genome under these circumstances. Here, we investigated
whether the Arabidopsis thaliana DNA methylation
status is altered in tissues responding to the attack of Pseudomonas
syringae pv. tomato DC3000. We applied amplified
fragment length polymorphism analysis to monitor
cytosine methylation at anonymous 5´-CCGG-3´ and 5´-
GATC-3´sites in naïve and infected samples. Plant genomic
fragments reducing methylation upon infection, including
peri/centromeric repeats such as the 180-bp unit, Athila
retrotansposon, and a portion of the nuclear insertion of
mitochondrial DNA, were isolated and characterized. P. syringae
pv. tomato-induced hypomethylation was detected
by high-performance liquid chromatography assays and at
the molecular level it did not seem to equally affect all 5-
methyl cytosine (5-mC) residues. Nuclei from challenged
tissues displayed structural chromatin alterations, including
loosening of chromocenters, which also were stimulated
by avirulent P. syringae pv. tomato, but not by the P. syringae
pv. tomato hrpL mutant. Finally, P. syringae pv. tomato induced
hypomethylation was found to occur in the absence
of DNA replication, suggesting that it involves an active
demethylation mechanism. All these responses occurred at
1 day postinfection, largely preceding massive plant cell
death generated by pathogen attack.