Two wild plant species regulate flooding survival through distinct mechanisms

Flooding events are increasing with global climate change and play a vital role in vegetation dynamics, but also seriously impact crop productivity. Here using genome-scale technologies we identify novel processes of two different strategies of plant adaptation to flooding stress: submergence-escape through shoot elongation in the frequently flooded plant Rumex palustris and submergence-induced quiescence in the rarely flooded species Rumex acetosa. We provide evidence for pronounced transcriptional control in R. acetosa of genes encoding metabolic enzymes associated with energy conservation typical of the quiescence survival strategy. The escape strategy of R. palustris, on the other hand, is accompanied by a strong regulation of genes previously associated with photomorphogenesis and shade avoidance, but shown here to be under tight control of accumulated ethylene during submergence. Furthermore, we demonstrate that the submergence escape species displays ethylene-induced priming of anoxia tolerance, through enhanced induction of anoxia tolerance genes. We conclude that contrasting ecological flooding survival strategies are regulated through distinct physiological and molecular mechanisms identified here.