|Rogers Jr, Hugo|
|Prior, Stephen - Steve|
Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1999
Publication Date: N/A
Interpretive Summary: Elevated atmospheric CO2 changes plant development which leads to altered plant structure. The size and shape of leaves, stems, branches and roots determines how much food crop species are able to produce, and in natural ecosystems, how plants are able to compete with each other for shared water, light and nutrients. We reviewed existing data on plant structural responses to elevated CO2 and have provided recommendations for further research. The recommendations provided will help scientists from around the world to focus research efforts on the most crucial, and least understood, aspects of plant structural responses to rising global CO2 levels, and will allow us to better understand impacts of increasing CO2 on natural and agricultural plant systems.
Technical Abstract: Consequences of increasing atmospheric CO2 concentration on plant structure, an important determinant of physiological and competitive success, have not received sufficient attention in the literature. Understanding how increasing carbon input will influence plant developmental processes, and resultant form, will help bridge the gap between physiological response and ecosystem level phenomena. Growth in elevated CO2 alters plant structure through its effects on both primary and secondary meristems of shoots and roots. A review of the literature suggests that cell division, cell expansion, and cell patterning may be affected, driven mainly by increased substrate (sucrose) availability and perhaps also by differential expression of genes involved in cell cycling (e.g., cyclins) or cell expansion (e.g., xyloglucan endotransglycosylase). Increased leaf growth results more often from increased cell expansion rather than increased division. Few studies, however, have quantified spatial relationships among chlorenchyma cells (size, orientation, and surface area), intercellular spaces, and conductive tissue. Greater leaf size and/or more leaves per plant are often noted in plants grown in elevated CO2. The ratio of internode length to node number often increased, but the length and number of branches per node was greater, suggesting reduced apical dominance. Data concerning effects of elevated CO2 on stem/branch anatomy, vital for understanding potential shifts in functional relationships of leaves with stems, roots with stems, and leaves with roots, are too few to make generalizations. Altered branching characteristics in both shoots and roots may impact competitive relationships above and below the ground.