|Gesch, Russell - Russ|
|Allen, Leon - Hartwell|
Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/7/2002
Publication Date: 8/7/2002
Citation: GESCH, R.W., KANG, I., GALLO-MEAGHER, M., VU, J.C., BOOTE, K.J., ALLEN JR, L.H., BOWES, G. PHOTOSYNTHETIC ADJUSTMENTS IN TWO RICE ECOTYPES TO HIGH GROWTH CO2 AND TEMPERATURE. AMERICAN SOCIETY OF PLANT BIOLOGISTS. 2002. ABSTRACT P. 137.
Technical Abstract: Rice (Oryza sativa L.) photosynthetically acclimates to elevated CO2 and is sensitive to high temperatures. However, little is known about intra-specific responses to elevated CO2 and temperature, although genetic modifications will likely be needed to cope with global climate changes. This study compared adjustments in the photosynthetic apparatus of two rice ecotypes to elevated CO2 and temperature. IR72 (Indica) and M103 (Japonica) rice were paddy cultured in sun-lit, environment-controlled chambers under ambient (350 ppm) and elevated (700 ppm) CO2 and day/night temperatures ranging from 28/18 to 40/30 deg C. At elevated CO2, leaf photosynthesis in M103 declined with temperature, while that of IR72 increased from 28 to 34 deg C before decreasing at 40 deg C. At ambient CO2, the rates were lower for both cultivars with little response to temperature. Rubisco activity and protein content declined with elevated CO2 and temperature, but the response was greater for M103. Rubisco protein decreased as much as 50% in M103 due to high CO2. Between 28 and 40 deg C, Rubisco protein in IR72 leaves declined 20 and 24% under ambient and elevated CO2, respectively, while it was reduced by 47 and 69%, respectively, in M103. Under ambient CO2, rbcS expression increased in IR72 with temperature, while it decreased for M103 under both CO2 treatments. Measurements of FV/FM showed that neither high temperature or CO2 affected the photochemical efficiency of PSII. There was a small, but consistent increase in psbA (codes for D1 protein of PSII) expression for IR72 with temperature, whereas M103 declined slightly. Genotypic variation appears to exist in rice for carboxylation responses to elevated CO2 and temperature.