PARENT SESSION
Posters P3D Genomic, proteomic and related technologies. Abstracts (720-730)

Mutant screening by kinetic fluorescence imaging. Marja Hakala^*,1, Marius Codrea², Ladislav Nedbal³, Olli Nevalainen², Tero Aittokallio², Esa Tyystjärvi¹, ¹ Department of Biology, Turku, Finland² Turku Centre for Computer Science, Turku, Finland³ Institute of Landscape Ecology, Nove Hrady, Czech Republic

ABSTRACT- Chlorophyll fluorescence is rich in information about the photosynthetic machinery. Much of this information can be extracted only if the yield of chlorophyll fluorescence is monitored as a function of time after a light-to-dark transition. We have developed a method for non-invasive high-throughput screening of mutant libraries in order to disclose photosynthesis-related phenotypic effects of the mutations. The method can also be used to rapidly select homozygous individuals for a genetically pure line, for example in studying mutants from insertion mutant collections. We tested the methods by screening 38 different photosynthesis-related Arabidopsis mutants together with the wild type. Plants were grown for two weeks on Agar, and the fluorescence signal was captured with a CCD camera during a complex illumination series including several light intensities, dark periods and saturating pulses. In order to find differences in the time-course of the fluorescence yield in mutant plants compared to the wild-type plants, we extracted a set of 40 features from each fluorescence curve (arising from one pixel). In addition to using fluorescence features that have well-established PSII-related interpretations, features describing the form of the fluorescence curve were used. The Mahalanobis distance was employed as a measure of the difference between set of features extracted from the mutant plants and the average features of the wild type plants. Plants that have mutations affecting any feature of the fluorescence curve were picked up from a false color photograph of the sample, with each pixel colored according to its Mahalanobis distance score. We were able to detect different psbS deficient, zeaxanthin-deficient and zeaxanthin epoxidase deficient mutants, three Rubisco activase mutants, digalactocylglycerol deficient mutants, a "lighter color" mutant and one pleiotropic mutation. We conclude that more photosynthesis mutants can be found with this method than with traditional measurements focusing to one fluorescence parameter, like NPQ.

KEY WORDS: chlorophyll a fluorescence, mutant screening, Arabidopsis thaliana, kinetic imaging