Details

Autor(en) / Beteiligte

• Cousins, AB
• Adam, N R
• Wall, G W
• Kimball, BA
• Pin, PJ Jr
• Leavitt, S W
• LaMorte, R L
• Matthias, AD
• Ottman, MJ
• Thompson, T L
• Webber, AN

Titel

Reduced photorespiration and increased energy-use efficiency in young CO sub(2)-enriched sorghum leaves

Ist Teil von

• The New phytologist, 2001-05, Vol.150 (2), p.275-284

Erscheinungsjahr

2001

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• To determine the response of C sub(4) plants to elevated CO sub(2) it is necessary to establish whether young leaves have a fully developed C sub(4) photosynthetic apparatus, and whether photosynthesis in these leaves is responsive to elevated CO sub(2). The effect of free-air CO sub(2) enrichment (FACE) on the photosynthetic development of the C sub(4) crop Sorghum bicolor was monitored. Simultaneous measurements of chlorophyll a fluorescence and carbon assimilation were made to determine energy utilization, quantum yields of carbon fixation ( phi CO sub(2)) and photosystem II ( phi PSII), as well as photorespiration. Assimilation in the second leaf of FACE plants was 37% higher than in control plants and lower apparent rates of photorespiration at growth CO sub(2) concentrations were exhibited. In these leaves, phi PSII: phi CO sub(2) was high at low atmospheric CO sub(2) concentration (Ca) due to overcycling of the C sub(4) pump and increased leakiness. As Ca increased, phi PSII: phi CO sub(2) decreased as a greater proportion of energy derived from linear electron transfer was used by the C sub(3) cycle. The stimulation of C sub(4) photosynthesis at elevated Ca in young leaves was partially due to suppressed photorespiration. Additionally, elevated Ca enhanced energy-use efficiency in young leaves, possibly by decreasing CO sub(2) leakage from bundle sheath cells, and by decreasing overcycling of the C sub(4) pump.