Biological adaptive mechanisms displayed by a freshwater plant to live in aquatic and terrestrial environments

Abstract

Wetlands are strongly affected by seasonal hydrological changes and extreme drought events that can cause low water levels. In response, some freshwater plants can produce emergent growth forms that experience a drastic change in environmental conditions. Potamogeton wrightii is a freshwater plant, which grows primarily underwater but can also produce terrestrial shoots when emerged. The objective of this study was to investigate the anatomical and physiological responses of P. wrightii to these two distinct environments, as well as the genetic responses behind them. Aerial leaves of P. wrightii were thicker, and had larger amounts of cutin and wax, developed stomata, had a greater tolerance to strong light, and a greater photochemical efficiency. In contrast, submerged leaves had a greater ability to use HCO3− and to synthesize photosynthetic pigments. The differentially expressed genes including cutin and wax biosynthesis, photosynthesis-antenna proteins and photosynthesis pathways, clarified the molecular adaptive mechanisms in P. wrightii to aquatic and terrestrial environments. The capacity of P. wrightii to survive fluctuating water level can be attributed to its genotype that resulted from its evolution from land plants and its phenotypic plasticity. Further work is needed to assess the possibility and costs of aerial leaves to survive when re-submerged.