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United States Department of Agriculture

Agricultural Research Service

Title: Development of C4 Photosynthesis in Sorghum Leaves Grown under Free-Air Co2 Enrichment (Face)

Authors
item Cousins, A - ARIZONA STATE UNIV
item Adam, Neal
item Wall, Gerard
item Kimball, Bruce
item Pinter Jr, Paul
item Ottman, M - UNIV OF ARIZONA
item Leavitt, S - UNIV OF ARIZONA
item Webber, A - ARIZONA STATE UNIV

Submitted to: Journal of Experimental Botany
Publication Type: Abstract Only
Publication Acceptance Date: April 22, 2003
Publication Date: August 1, 2003
Citation: COUSINS, A.B., ADAM, N.R., WALL, G.W., KIMBALL, B.A., PINTER JR, P.J., OTTMAN, M.J., LEAVITT, S.W., WEBBER, A.N. DEVELOPMENT OF C4 PHOTOSYNTHESIS IN SORGHUM LEAVES GROWN UNDER FREE-AIR CO2 ENRICHMENT (FACE). JOURNAL OF EXPERIMENTAL BOTANY. 2003.

Technical Abstract: The developmental pattern of C4 expression has been well characterized in maize and other C4 plants. However, few reports have explored the possibility that the development of this pathway may be sensitive to changes in atmospheric CO2 concentrations. Therefore, both the structural and biochemical development of leaf tissue in the fifth leaf of Sorghum bicolor plants grown at elevated CO2 have been characterized. Ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC) activities accumulate rapidly as the leaf tissue differentiates and emerges from the surrounding whorl. Rusisco was not expressed in a cell-specific manner in the youngest tissue at the base of the leaf, but did accumulate before PEPC was detected. This suggests that the youngest leaf tissue utilizes a C3-like pathway for carbon fixation. However, this tissue was in a region of the leaf receiving very low light and so significant rates of photosynthesis were not likely. Older leaf tissue that had emerged from the surrounding whorl into full sunlight showed the normal C4 syndrome. Elevated CO2 had no effect on the cell-specific localization of Rubisco or PEPC at any stage of leaf development, and the relative ratios of Rubisco to PEPC remained constant during leaf development. However, in the oldest tissue at the tip of the leaf, the total activites of Rubisco and PEPC were decreased under elevated CO2 implying that C4 photosynthetic tissue may acclimate to growth under elevated CO2.

Last Modified: 10/25/2014
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