STRESS RESPONSES AND METABOLIC-REGULATION OF GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE GENES IN ARABIDOPSIS

We report here effects of three environmental conditions, heat shock, anaerobic treatment, and carbon source supply, on expression of nuclear genes encoding chloroplast (GapA and GapB) and cytosolic (GapC) glyceraldehyde-3-phosphate dehydrogenase from Arabidopsis thaliana. The steady-state mRNA level of the GapC increased when Arabidopsis plants were transferred from normal growth condition to heat-shock, anaerobiosis, or increased sucrose supply conditions. In contrast, the steady-state mRNA levels for GapA and GapB genes were unaffected or decreased transiently under the same treatments. To identify the cis-acting regulatory elements, transgenic tobacco plants containing a 820-bp GapC 5'-flanking DNA fragment and beta-glucuronidase (Gus) fusion were constructed. Analyses of these transgenic plants indicate that this 820-bp DNA fragment is sufficient to confer both heat-shock and anaerobic responses. These results suggest that transcriptional level control is involved in regulation of GapC expression under these stress conditions. Histochemical analysis of Gus activity indicates that expression of the GapC is cell-type specific and is probably linked to the metabolic activity of the cells.