TY - JOUR
T1 - Surviving floods: leaf gas films improve O2 and CO2 exchange, root aeration, and growth of completely submerged rice
AU - Pedersen, Ole
AU - Rich, Sarah Meghan
AU - Colmer, Timothy David
N1 - KEYWORDS
plastrons • diffusive boundary layers • underwater photosynthesis • internal aeration • submergence tolerance • Oryza sativa
PY - 2009
Y1 - 2009
N2 - When completely submerged, the leaves of some species retain a surface gas film. Leaf gas films on submerged plants have recently been termed 'plant plastrons', analogous with the plastrons of aquatic insects. In aquatic insects, surface gas layers (i.e. plastrons) enlarge the gas–water interface to promote O2 uptake when under water; however, the function of leaf gas films has rarely been considered. The present study demonstrates that gas films on leaves of completely submerged rice facilitate entry of O2 from floodwaters when in darkness and CO2 entry when in light. O2 microprofiles showed that the improved gas exchange was not caused by differences in diffusive boundary layers adjacent to submerged leaves with or without gas films; instead, reduced resistance to gas exchange was probably due to the enlarged water–gas interface (cf. aquatic insects). When gas films were removed artificially, underwater net photosynthesis declined to only 20% of the rate with gas films present, such that, after 7 days of complete submergence, tissue sugar levels declined, and both shoot and root growth were reduced. Internal aeration of roots in anoxic medium, when shoots were in aerobic floodwater in darkness or when in light, was improved considerably when leaf gas films were present. Thus, leaf gas films contribute to the submergence tolerance of rice, in addition to those traits already recognized, such as the shoot-elongation response, aerenchyma and metabolic adjustments to O2 deficiency and oxidative stress.
AB - When completely submerged, the leaves of some species retain a surface gas film. Leaf gas films on submerged plants have recently been termed 'plant plastrons', analogous with the plastrons of aquatic insects. In aquatic insects, surface gas layers (i.e. plastrons) enlarge the gas–water interface to promote O2 uptake when under water; however, the function of leaf gas films has rarely been considered. The present study demonstrates that gas films on leaves of completely submerged rice facilitate entry of O2 from floodwaters when in darkness and CO2 entry when in light. O2 microprofiles showed that the improved gas exchange was not caused by differences in diffusive boundary layers adjacent to submerged leaves with or without gas films; instead, reduced resistance to gas exchange was probably due to the enlarged water–gas interface (cf. aquatic insects). When gas films were removed artificially, underwater net photosynthesis declined to only 20% of the rate with gas films present, such that, after 7 days of complete submergence, tissue sugar levels declined, and both shoot and root growth were reduced. Internal aeration of roots in anoxic medium, when shoots were in aerobic floodwater in darkness or when in light, was improved considerably when leaf gas films were present. Thus, leaf gas films contribute to the submergence tolerance of rice, in addition to those traits already recognized, such as the shoot-elongation response, aerenchyma and metabolic adjustments to O2 deficiency and oxidative stress.
U2 - 10.1111/j.1365-313X.2008.03769.x
DO - 10.1111/j.1365-313X.2008.03769.x
M3 - Journal article
C2 - 19077169
SN - 0960-7412
VL - 58
SP - 147
EP - 156
JO - Plant Journal
JF - Plant Journal
IS - 1
ER -