Plants have to deal with fast and strong changes in their environment. One of the fastest is the light quantity, changes from low amounts of light in the shade to extreme high amounts of light in the full sun can occur in seconds. A quite complex cascade of events are induced that try to prevent photoinhibition due to photooxidation of the reaction centers of the photosystems in plants. This involves for example the activation of the xanthophyll cycle enzyme vialaxanthin de-epoxidase that converts violaxanthin via antheraxanthin to zeaxanthin and other at present not yet fully understood. This adaption step is called short-term acclimation.
If the plant is acclimated to high light for a longer period, other mechanisms start to adapt the photosystems to the environment. To these long term acclimation steps belongs the regulation of the antenna size, accumulation of protection pigments like anthocyanins and the upreguation of a couple of genes that are related to the light harvesting antenna genes the so called Lil genes (light harvesting like genes) and PsbS.
In this project I like to elucidate more of the function of these Lil gene products and the mechanisms that are involved in high light protection. Therefore I will create mutants lacking specific Lil genes and characterize their phenotype in order to find out their function. This will be done for the Lil 2 and Lil 3 gene by antisense inhibition and or T-DNA tagging. Furthermore I will continue to characterize a mutant lacking the PsbS gene (NPQ 4 mutant).
Picture: This is a mature plant of Arabidopsis thaliana.
Methods used in this project will not only be Agrobacterium tumefaciens mediated transformation of Arabidosis thaliana plants, Western blots to analyze mutants, Northern and Southern blots to investigate the genotype of the mutants, but also biochemical methods like HPLC and as a new method, ecologically investigations of the fitness of certain mutants compared to the wild type in different growth conditions. By changing single environmental factors the regulation of the genes can be determined.
