The expression of Arabidopsis glutamate dehydrogenase gene gdh2 is induced under the influence of tetrapyrrole synthesis inhibitor norflurazon

Abstract

The gdh2 gene encoding beta-subunit of glutamate dehydrogenase in Arabidopsis belongs to diurnal-regulated genes. Its expression is highly increased in the dark and reduced to minimal rates at the day light. Some sugar-responsive regulatory pathways are known to be involved in the gdh2 light repression, but the specific mechanisms of this regulation are unknown. In our experiments expression of gdh2 gene increased 6-11 fold in Arabidopsis seedlings grown in presence of the tetrapyrrole synthesis inhibitor norflurazon. The increasing rate depended on the light intensity and did not correlate with the induction of ROS marker genes. This observation can be explained by both a low glucose level in the cells treated with norflurazon and absence of repression by the chloroplast-to-nucleus retrograde pathways because of chloroplast dysfunction. We assume that the diurnal regulation of gdh2 gene expression involves not only sugar-dependent, but also chloroplast-to-nucleus regulatory signals.

Keywords

• glutamate dehydrogenase
• retrograde regulation of gene expression
• chloroplast-to-nucle us signals
• Arabidopsis thaliana