Analysis of an Arabidopsis mutant with altered stress responses
MetadataShow full item record
Plants face a variety of conditions that cause biotic and abiotic stress. Since plants are sessile, and therefore cannot move to escape stressful conditions, they have evolved complex strategies to survive harsh environments. One such strategy is the ability to quickly alter the expression of genes, which, in effect, acclimates the plant. Glutathione S-transferases (GST) are an example of these genes that are induced under stressful conditions. In order to identify the mechanisms that regulate stress responsive gene expression, I used a genetic strategy to identify stress signaling mutants in which the luciferase (LUC) reporter was expressed under control of the stressresponsive Arabidopsis GST6 promoter. After chemical mutagenesis by ethyl methanesulfonate (EMS), a number of potential mutants that affect the expression of the GST6:LUC reporter gene, and presumably, the stress signaling pathways were isolated. One of the mutants, cdg6 (constitutively down-regulated GST6), is dominant and has altered responses to abscisic acid (ABA), ethylene, and salicylic acid (SA). In addition, physiological studies of cdg6 mutant plants showed that the gene is not involved in the ethylene signaling or synthesis pathways. A transcriptional profile of cdg6 using microarray analysis gave us a genome-wide view of gene expression alterations in mutant plants compared to the wild type plants. This analysis showed that endogenous GST genes are down regulated in cdg6, while a number of defense related genes such as chitinase were up regulated. These data indicate that cdg6 may represent a mutation in a gene that regulates defense responses.