PARENT SESSION
Posters P6B Photosynthetic acclimation: Mechanisms and gene expression. Abstracts (531-578)

Effect of altered capacity for feedback de-excitation. Carsten Külheim^*,1, Oskar Skogström¹, Stefan Jansson¹, ¹ Umeå Plant Science Center, Umeå, Västerbotten, Sweden

ABSTRACT- @ture have to cope with a variety of biotic and abiotic stresses. Many abiotic stresses lead to over-excitation of the photosynthetic apparatus. Feedback de-excitation is a process that protects photosystem II from damage in case of over-excitation on a short-term base. For this study we grew Arabidopsis thaliana plants with altered capacity for feedback de-excitation (npq4 with low capacity, wt with medium capacity and oePsbS with a high capacity for feedback de-excitation) in the field. We measured the growth and the fitness of these plants and found that a high capacity for feedback de-excitation leads to an increased growth and fitness. The fitness in the npq4 mutant was 60 % of the wt (1), the one of the oePsbS 120 % of the wt. The differences in growth were less pronounced. Some of the physiological parameters we measured showed differences between the genotypes e.g. the npq4 mutant started to accumulate anthocyanins earlier than the wt and to a higher extent, total carbohydrate pools were lower in the leaves of npq4 leaves at the point of flowering. We also measured photosynthetic parameters directly in the field using a FluorCam. During the growth we took samples for global expression studies and global metabolite analysis. We also performed global expression analysis from two poplar lines with reduced amounts of PsbS, where one line has 50 % PsbS protein and the other line less than 5 %. In this study several genes for stress response were upregulated in the mutant lines vs. the wt. (1) C. Kulheim, J. Agren, S. Jansson (2002) Rapid regulation of light harvesting and plant fitness in the field Science 297 91-93

KEY WORDS: fitness, feedback de-excitation