Hypoxic gene expression in med25-1

Plants as obligate aerobic organisms are severely affected by flooding-induced oxygen restriction. As a consequence, they suffer from energy deficits which are counterbalanced by activation of anaerobic metabolism genes through subgroup VII ETHYLENE-RESPONSE FACTOR (ERFVII) transcription factors. Despite the crucial role of ERFVIIs in regulating transcript responses to hypoxia in multiple plant species, it is not understood how these factors mechanistically initiate hypoxic gene expression. Here, we show that the Arabidopsis ERFVIIs RELATED TO APETALA 2.12 (RAP2.12) and RAP2.2 recruit the Mediator complex, present in all higher eukaryotes, in order to convey stress signals to RNA polymerase II. This is achieved by specific interaction with Mediator subunit 25 (AtMED25). Both RAP2.12 and RAP2.2 require AtMED25 for full activity and subsequent induction of target hypoxia core genes. Our findings support an interplay of multiple coactivators under hypoxia and underline the flexible nature of the Mediator complex composition, which both help to meet specific cellular demands under (hypoxic) stress conditions. Overall design: 1 control, 1 treatment (3h 1% O2), wildtype and med25-1 plants, 3 biological replicates per genotype and treatment)