Poster: Photosynthesis
Abs #
367: IIdentification of Arabidopsis mutants defective in high light response using chlorophyll fluorescence monitoring system
Regulation of photosynthetic activity in response to high light is significant mechanism for plants to avoid photodamage. In order to investigate molecular mechanisms of this regulation, we employed imaging of chlorophyll fluorescence to screen the T-DNA-tagged Arabidopsis mutants with defects in high light response. For screening, Arabidopsis plants were exposed to high light (260 mE) for 24 hr. High-light treated plants were subjected to the measurements of chlorophyll fluorescence kinetics during excessive illumination (360 mE, 12 sec). To date, we screened 16,000 seedlings and isolated eighteen candidates showing different fluorescence kinetics from that of WT. Fluorescence kinetics of four mutants (16-7-1, 17-2-2, 25-8-15, 39-10-32) differed from WT only after the high-light treatment. Fourteen mutants showed different fluorescence kinetics from WT without high-light treatment. For further characterization of these mutants, steady state chlorophyll fluorescence was investigated by pulse-amplified modulated (PAM) chlorophyll fluorometry using two different actinic light intensities (80 mE and 700 mE). 16-7-1 showed a slightly reduced Fv/Fm. 17-2-2 and 39-10-32 showed a decrease in qP andƒ³II under high actinic light. 25-8-15 did not show significant difference from WT under steady state condition. Among the mutants showing altered fluorescence before the high-light treatment, seven mutants differed in photosynthetic parameters under steady state condition. Determination of the position of the insertion of T-DNA elements is now under way.
