The Altered Expression of Influences the Arabidopsis Response to Iron Deficiency.

MicroRNAs contribute to the adaptation of plants to varying environmental conditions by affecting systemic mineral nutrient homeostasis. Copper and iron deficiencies antagonistically control the expression of (), which post-transcriptionally regulates laccase-like multicopper oxidase family members , , and . In this work, we used T-DNA insertion mutants (408-KO1 and 408-KO2) and a previously characterized transgenic line overexpressing (35S:408-14) to explore how influences copper- and iron-dependent metabolism. We observed that the altered expression of diminished plant performance and the activation of the iron-regulated genes under iron-deficient conditions. Consistently with the low expression of the -target laccases, we showed that the vascular bundle lignification of the plants diminished. The decrease in the phenoloxidase and ferroxidase activities exhibited by wild-type plants under iron deficiency did not occur in the 408-KO1 plants, probably due to the higher expression of laccases. Finally, we observed that the hydrogen peroxide levels under iron starvation were altered in both the and lines. Taken together, these results suggest that Arabidopsis plants with modified levels undergo multiple deregulations under iron-deficient conditions.