With the intensification of global climate change, the frequency and severity of floods have sharply increased. To adapt to flooded environments, plants have evolved a series of adaptive phenotypes, including aerenchyma and adventitious roots, enlarged stomata, internode and petiole elongation, and inhibition of high-energy metabolism processes. However, no single strategy can fully explain the different ways in which plants adapt to flood stress.

Recently, a research group led by Prof. HOU Hongwei from the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences highlighted key advances in understanding plant adaptation to water stress. Their article was published in Plant, Cell & Environment. 

The researchers systematically elaborate on two types of adaptive strategies adopted by model plants such as rice and watercress in response to waterlogging stress. One is the low oxygen quiescence strategy (LOQS), characterized by the inhibition of plant metabolism and growth during waterlogging, and the ability to quickly restore growth after the flood subsides. It is more common in species that can tolerate short-term deep floods.

The second is the low oxygen escape strategy (LOES), characterized by the rapid elongation of stems or leaves in a short period of time, exposing the surface of shallow floods to achieve gas exchange and photosynthesis. 

The article also defines "Heterophylly" in aquatic plants as the third adaptation strategy. Unlike LOQS and LOES, heterophyllous plants develop the “Variation” strategy: they can produce aquatic leaves when the water level rises and terrestrial leaves when the water level drops. 

The researchers discuss the molecular mechanisms and omics research progress of heterophylly regulation and point out its limitations and future development directions. They also introduce the photosynthetic plasticity strategies of aquatic plants in different environments and the developmental plasticity strategies during floating growth. 

The article proposes applying the diverse adaptation strategies of aquatic plants to future crop improvement and agricultural production, with approaches including horizontal gene transfer (HGT) and specific expression of heterophylly regulatory genes.

The morphology of four typical heterophyllous plants (Image by IHB)

(Editor: MA Yun)