International Society for Plant Anaerobiosis

International Society for Plant Anaerobiosis - flooded Rumex crispus (c) Ole Pedersen

   

CONFERENCES - International Society for Plant Anaerobiosis (ISPA)


 

Submergence tolerance of plants: leaf gas films enhance oxygen and carbon dioxide exchange under water

 

Colmer TD1 & Pedersen O2

 

1) The University of Western Australia, Australia; 2) University of Copenhagen, Denmark

 

Submergence can impact on terrestrial plants in wetlands and other low-lying areas. Plant survival underwater depends upon gas exchange for respiration (O2) and photosynthesis (CO2). Leaves of many wetland species (e.g. Phragmites australis, Phalaris arundinacea, Oryza sativa, Hordeum marinum) retain a thin surface layer of gas when under water. Leaf gas films facilitate O2 and CO2 exchange with floodwaters. As examples, with gas films present: (i) O2 uptake rates in darkness were up to 5-fold higher, and (ii) CO2 uptake during light periods (i.e. net photosynthesis) was enhanced up to 6-fold, as compared with when these films had been removed. Improved O2 entry during darkness and higher net photosynthesis during light periods, in submerged shoots, both enhanced internal O2 movement via aerenchyma to roots in an anoxic substrate. When plants were submerged for 7 days with gas films removed, tissue 29 sugars declined and shoot and root growth were reduced, compared to submerged plants with intact gas films. In summary, leaf gas films enhance O2 and CO2 exchange during submergence, resulting in higher O2 in tissues and more CO2 for photosynthesis, and thus contribute to submergence tolerance of some plants.