IDENTIFICATION OF DNA CONTROL ELEMENTS RESPONSIVE TO SPECIFIC STIMULI

摘要

In order to identify genes whose proteins are involved in the regulation of SAR downstream of cell death, a screen was carried out to isolate mutants that constitutively express SAR. The PR-1 promoter, the most reliable marker for the onset of SAR, was cloned in front of the firefly (Photinus pyralis) luciferase reporter gene and transformed into Arabidopsis. A transgenic line with a luciferase expression pattern that paralleled expression of the endogenous PR-1 gene was identified and subjected to EMS mutagenesis to isolate mutants that constitutively expressed the PR-1/luciferase gene. Biochemical, cytological, pathological, and genetic methods were employed to further characterize the mutants and to prove the isolation of SAR mutants downstream of cell death. This characterization enables one to distinguish between classes of cim mutants, and to describe physiological changes that occur during the maintenance phase of SAR. Furthermore, utilizing microarray chips, the entire plant genome was simultaneously surveyed for genes that change in expression in response to biotic and abiotic factors. By comparing gene expression changes across various treatments, groups of co-regulated genes (regulons) were identified and the genomic sequences of genes within a regulon were examined to identify common sequence motifs that are likely to act as regulatory elements. This approach used experimental design based upon the biology of the study system in combination with bioinformatics to analyze the results.