A METHOD FOR MEASURING WHOLE-PLANT PHOTOSYNTHESIS IN ARABIDOPSIS-THALIANA

Measurement of photosynthesis of intact leaves of intact leaves of Ara bidopsis thaliana has been prohibitive due to the small leaf size and prostrate growth habit. Because of the widespread use of Arabidopsis f or plant science research it is important to have a procedure for accu rate, nondestructive measurement of its photosynthesis. We developed a nd tested a method for analysis of photosynthesis in whole plants of A rabidopsis. Net carbon assimilation and stomatal conductance were meas ured with an open gas exchange system and photosynthetic oxygen evolut ion was determined from chlorophyll fluorescence parameters. Individua l plants were grown in 50 cubic centimeter tubes that were attached wi th an air tight seal to an enclosed gas exchange chamber for measureme nt of carbon dioxide and water exchange by the whole plant. Chlorophyl l fluorescence from intact leaves was simultaneously measured with a p ulse modulated fluorometer. Photosynthetic CO2 assimilation and stomat al conductance rates were calculated with established gas exchange pro cedures and O-2 evolution was determined from chlorophyll fluorescence measurement of Photosystem II yield. Carbon assimilation and oxygen e volution in response to light intensity and ambient CO:! concentration was measured and is presented here to demonstrate the potential use o f this method for investigation of photosynthesis of Arabidopsis plant s in controlled environment conditions.