Abstract
In the plant respiratory-chain, the ATP-uncoupling cyanide-resistant pathway, catalyzed by alternative oxidase (AOX), is supposed to prevent ROS production and maintain carbon to nitrogen (CN) ratio. In this study, we investigated whether AOX contributes to control CN ratio under low-N condition. We treated Arabidopsis thaliana WT and aox knock-out transgenic with short- or long-term low-N. In WT, cyanide-resistant respiratory rate and AOX expression increased after the short-term low-N treatment. Total respiratory rate in aox was similar to that of WT. Some intermediates increased under low-N condition, and those of aox were lower than WT. In long-term low-N treatment, growth of aox was greater than that of WT. These results suggest that the decrease of intermediate levels in aox leads to higher growth in long-term N deficiency. There was no significant difference in CN ratio between the genotypes, suggesting that AOX does not contribute to control CN ratio under low-N condition.
