High-density nodal diaphragms in stems slow down, but do not obstruct, longitudinal oxygen diffusion during partial submergence

Journal of Experimental Botany, vol. 77, pp. 1267–1278

Abstract

The species Alternanthera philoxeroides is a flood-tolerant plant that has to cope with the hypoxic stress under submergence. However, the pith cavity in stems of this species is interrupted and partitioned by low-porosity diaphragms at the nodes. To date little knowledge is available about whether discontinuous pith cavities are functional for internal gas transport in plants. To disclose the role of stem discontinuous pith cavities in internal gas transport, the diffusive transport capacity of O2, the tissue O2 status of intact plants, and the influence of restricting longitudinal O2 supply on whole-plant growth during partial submergence were assessed. We found that stem pith cavities were the main pathway for diffusional supply of molecular O2; blocking only one internode significantly decreased the O2 flux to lower internodes, and the reduced O2 flux translated into reduced growth in partially submerged plants. A major output component of the study is a model that uses normalized tissue dimensions and concentration gradients to establish a fair foundation for comparison of contrasting species under different experimental conditions. We therefore predict that future studies will use this approach to further broaden the scope and value of resistance and flux measurement in target species.

Authors 7

1. Qiaoli Ayi

   Southwest University

   Affiliation as printed

   Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing Key Laboratory of Plant Ecology and Resources in Three Gorges Reservoir Region, School of Life Sciences, Southwest University , Beibei, Chongqing 400715 ,

2. Xiaoping Zhang

   Southwest University

   Affiliation as printed

   Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing Key Laboratory of Plant Ecology and Resources in Three Gorges Reservoir Region, School of Life Sciences, Southwest University , Beibei, Chongqing 400715 ,

3. Ole Pedersen

   University of Copenhagen · The University of Western Australia

   Affiliation as printed

   Department of Biology, University of Copenhagen , Copenhagen 2100 ,

   School of Biological Sciences, The University of Western Australia , Crawley, WA 6009 ,

4. Peter M. van Bodegom Aachen Institute of Environmental Sciences (CML)

   Leiden University

   Affiliation as printed

   Institute of Environmental Sciences, Leiden University , 2333 CC, Leiden ,

5. Qian Wang

   Southwest University

   Affiliation as printed

   Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing Key Laboratory of Plant Ecology and Resources in Three Gorges Reservoir Region, School of Life Sciences, Southwest University , Beibei, Chongqing 400715 ,

6. Binghui He

   Southwest University

   Affiliation as printed

   College of Resources and Environment, Southwest University , Beibei, Chongqing 400715 ,

7. Johannes H. C. Cornelissen

   Vrije Universiteit Amsterdam

   Affiliation as printed

   Department of Systems Ecology, Faculty of Earth and Life Sciences, Institute of Ecological Science, Vrije Universiteit Amsterdam , HV 1081 Amsterdam ,