Plant, Animal & Microbe Genomes X Conference Plant, Animal & Microbe Genomes X ConferenceJanuary 12-16, 2002
Town & Country Convention Center
San Diego, CA
Workshop: Abiotic Stress
Immediate defense response in plants to various biotic and abiotic stresses often involves a process called oxidative burst that accumulates reactive oxygen species (ROS), mainly superoxide (O2-) and hydrogen peroxide (H2O2), in the challenged plant tissue. H2O2 is an active signaling molecule and its accumulation leads to concerted gene expression and ultimately to enhanced stress and pathogen tolerance. However, the detailed mechanism by which H2O2 triggers defense responses in plants is still largely unknown. In an attempt to identify elements of the signaling pathways triggered by H2O2, we exposed Arabidopsis Col-0 plants to H2O2 and profiled gene expression at 0, 1, 3, 6, and 12 hrs using a DNA microarray representing the nearly 4400 genes on Arabidopsis chromosome 2. We have found a total of 541 genes significantly up- or down-regulated (at 95% confidence) at least one time point, which were then grouped into clusters based on expression pattern. One cluster showing high level expression peaking at 1 hr point include genes coding for PAL1 and GST6, two marker enzymes for oxidative stress. Our data showed up-regulation of a number of genes that may code for proteins involved in protection and defense. In addition to these, we observed various patterns of regulation with the genes that may encode components of the MAPK signaling pathway, plant hormone synthesis, Ca2+/calmodulin signaling systems, programmed cell death, guanine nucleotide-pool control, cell-cycle control, a ubiquitin/proteasome pathway, and transcription factors. The diversity of the expression patterns and the functional roles represented suggests the presence of an integrated network of signaling pathways linked to the H2O2 signal transduction pathway.