Extreme flooding tolerance in Rorippa

Low oxygen stress imposed by floods creates a strong selection force shaping plant ecosystems in flood-prone areas.
Plants inhabiting these environments adopt various adaptations and survival strategies to cope with increasing water
depths. Two Rorippa species, R. sylvestris and R. amphibia that grow in naturally flooded areas, have high submergence
tolerance achieved by the so-called quiescence and escape strategies, respectively. In order to dissect the molecular mechanisms
involved in these strategies, we investigated submergence-induced changes in gene expression in flooded roots of
Rorippa species. There was a higher induction of glycolysis and fermentation genes and faster carbohydrate reduction in
R. amphibia, indicating a higher demand for energy potentially leading to faster mortality by starvation. Moreover, R. sylvestris
showed induction of genes improving submergence tolerance, potentially enhancing survival in prolonged floods.
Additionally, we compared transcript profiles of these 2 tolerant species to relatively intolerant Arabidopsis and found that
only Rorippa species induced various inorganic pyrophosphate dependent genes, alternatives to AT P demanding pathways,
thereby conserving energy, and potentially explaining the difference in flooding survival between Rorippa and Arabidopsis.