The gene expression profiles of mitochondrial respiratory components in Arabidopsis plants with differing amounts of under high intensity light.

We compared the expression of mitochondrial alternative oxidase (AOX) and other non-phosphorylating respiratory components (NPhPs) in wild type and transgenic following short-term transfer of plants to higher irradiance conditions to gain more insight into the mechanisms of AOX functioning under light. The overexpressing line (XX-2) showed the highest amount of transcripts and AOX1A synthesis during the entire experiment, and many NPhPs genes were down-regulated after 6-8 h under the higher light conditions. Antisense AS-12 plants displayed a compensatory effect, typically after 8 h of exposure to higher irradiance, by up-regulating their expression of the majority of genes encoding AOX and other respiratory components. In addition, AS-12 plants displayed 'overcompensation effects' prior to their transfer to high light conditions, i.e., they showed a higher expression level of certain genes. As a result, the ROS content in AS-12, as in XX-2, was consistently lower than in the wild type. All NPhPs genes share, in common with , light- and stress-related -acting regulatory elements (CAREs) in their promoters. However, the expression of respiratory genes does not always depend on the level of expression. This suggests the presence of multiple combinations of signaling pathways in gene induction. Based on our results, we outline possible directions for future research.