PARENT SESSION

Symposium S8C C4 and CAM
Friday September 3rd, 2004 8:30 AM-10:30 AM Room 510B
Chair: Rowan Sage
Co-Chair: Howard Griffiths

¹³C and CAM photosynthesis. Klaus Winter^*,1, Joseph Holtum², ¹ Smithsonian Tropical Research Institute, Republic of Panama² James Cook University, Australia

ABSTRACT- ¹³C values have often been used to assess, in a semi-quantitative manner, the proportional contribution of nocturnal CO₂ fixation to plant carbon budgets. Recent research has improved the efficacy by which the ¹³C/¹²C ratio can be used as a measure of the expression of CAM photosynthesis in plants. Here, the following questions will be addressed: (1) How do ¹³C values correlate with the expression of CAM in the C₃-CAM plant Mesembryanthemum crystallinum? (2) Can ¹³C values be used to unravel the relative contributions of environmental and developmental factors in the control of the expression of CAM in M. crystallinum? (3) Can ¹³C values be used as an indicator of water-use efficiency in CAM plants? (4) How informative is the ¹³C value as an indicator of the expression of CAM amongst species in large-scale vegetation surveys?

KEY WORDS: crassulacean acid metabolism, water-use efficiency, carbon isotopes, mesembryanthemum crystallinum