Iron and ROS control of the DownSTream mRNA decay pathway is essential for plant fitness

A new regulatory pathway involved in plant response to oxidative stress was revealed using the iron-induced Arabidopsis ferritin AtFER1 as a model. Using pharmaco-logical and genetic approaches, the DownSTream (DST) cis-acting element in the 30-untranslated region of the AtFER1 mRNA was shown to be involved in the degrada-tion of this transcript, and oxidative stress triggers this destabilization. In the two previously identified trans-acting mutants (dst1 and dst2), AtFER1 mRNA stability is indeed impaired. Other iron-regulated genes containing putative DST sequences also displayed altered expression. Further physiological characterization identified this oxi-dative stress-induced DST-dependent degradation pathway as an essential regulatory mechanism to modulate mRNA accumulation patterns. Alteration of this control dramati-cally impacts plant oxidative physiology and growth. In conclusion, the DST-dependent mRNA stability control appears to be an essential mechanism that allows plants to cope with adverse environmental conditions