|Allen, Leon - Hartwell|
Submitted to: Journal of Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2000
Publication Date: N/A
Citation: N/A Interpretive Summary: Rice is one of the most important agricultural food crops in the world. For thousands of years prior to the industrial revolution terrestrial plants were exposed to much lower carbon dioxide [CO2] in the air than they experience today. The objective of this study by scientists at the University of Florida and USDA, ARS in Gainesville, FL, was to determine if rice, when exposed to lower than the ambient atmospheric [CO2] (i.e. ambient refers to the present [CO2] in the air at approximately 365 parts per million), has the capability to up-regulate leaf photosynthesis, and the gene expression, synthesis and activity of Rubisco, the primary protein responsible for absorbing atmospheric CO2 in most plants. When rice grown at ambient [CO2] was transferred to lower than ambient levels (subambient), photosynthesis of developing leaves initially decreased, but showed partial recovery after 10 days. The recovery was found mainly due to an up-regulation of Rubisco genetic expression leading to greater protein synthesis and activity of the enzyme. Thus, certain species of plants such as rice may adapt to grow at subambient [CO2] through up-regulation of Rubisco to optimize leaf photosynthesis performance.
Technical Abstract: To test the hypothesis whether low atmospheric [CO2] can cause an up- regulation of photosynthetic capacity, rice (Oryza sativa L.) growing under ambient [CO2] at 350 mmol mol-1 was switched to subambient [CO2] at 175 mmol mol-1 during late vegetative stage. After the switch, photosynthesis rate of developing leaves initially declined but partially recovered after 10 days. The rbcS expression in developing leaves increased within three days to almost twice that of ambient controls, followed later by an up-regulation of Rubisco total activity and content.