How plants breathe under water
Two rice leaves emerge from floodwater. The one on the right has superhydrophobic cuticles, and thus the submerged portion of the leaf traps a thin layer of gas (visible as a silvery sheen). The leaf on the left has been brushed with a dilute detergent to remove hydrophobicity and prevent the gas film from forming.
The photo shows how effective the superhydrophobic properties of rice leaves are, and one way of manipulating them. A study by Ole Pedersen and colleagues, recently published in New Phytologist, describes a rice mutant that lacks the nano coating of fine wax platelets that confers hydrophobic properties. The researchers can use this mutant to study the physiological function of the leaf gas films without using a detergent to manipulate the cuticle.
Pedersen, Colmer, Ashikari and colleagues aimed to identify the gene(s) responsible for the production of wax platelets that cover the leaf cuticle of rice leaves. The retention of a leaf gas film (the consequence of superhydrophobicity) greatly enhances the flood tolerance of many natural wetland plants, including rice. The leaf gas films act like gills, by enabling gas exchange (oxygen and carbon dioxide) with the floodwater.
This property isn’t limited to plants. Damsel flies and spiders are among terrestrial animals that visit the underwater world by using their superhydrophobic body surfaces to trap a thin layer of gas – that allows them to breathe below the surface, like an insect scuba tank. Pedersen and colleagues demonstrated this beneficial feature for wetland plants in 2008, and have now identified a gene crucial in controlling it.
Read the paper: Kurokawa, Y., Nagai, K., Huan, P. D., et al. (2018) Rice leaf hydrophobicity and gas films are conferred by a wax synthesis gene (LGF1) and contribute to flood tolerance. New Phytologist. doi: 10.1111/nph.15070
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Mike Whitfield (@mgwhitfield)