A method for measuring whole plant photosynthesis in Arabidopsis thaliana

Measurement of photosynthesis of intact leaves of intact leaves of Arabidopsis thaliana has been prohibitive due to the small leaf size and prostrate growth habit. Because of the widespread use of Arabidopsis for plant science research it is important to have a procedure for accurate, nondestructive measurement of its photosynthesis. We developed and tested a method for analysis of photosynthesis in whole plants of Arabidopsis. Net carbon assimilation and stomatal conductance were measured with an open gas exchange system and photosynthetic oxygen evolution was determined from chlorophyll fluorescence parameters. Individual plants were grown in 50 cubic centimeter tubes that were attached with an air tight seal to an enclosed gas exchange chamber for measurement of carbon dioxide and water exchange by the whole plant. Chlorophyll fluorescence from intact leaves was simultaneously measured with a pulse modulated fluorometer. Photosynthetic CO2 assimilation and stomatal conductance rates were calculated with established gas exchange procedures and O-2 evolution was determined from chlorophyll fluorescence measurement of Photosystem II yield. Carbon assimilation and oxygen evolution in response to light intensity and ambient CO:! concentration was measured and is presented here to demonstrate the potential use of this method for investigation of photosynthesis of Arabidopsis plants in controlled environment conditions.