Photosynthesis in fluctuating light : pgr5 suppressor mutant screen : low NPQ mutant identification and characterization Light is the essential energy source for plants to drive photosynthesis. In nature light availability is highly variable and often fluctuates on very short time scales. As a result plants developed mechanisms to cope with these fluctuations. Understanding how to improve light use efficiency in natural fluctuating light (FL) conditions is a major target for agronomy. In the first project we identified an Arabidopsis thaliana plant that showed reduced levels of rapidly inducible non photochemical quenching (NPQ). This plant was devoid of any T DNA insertion. Using a mapping by sequencing approach we successfully located the causal genomic region near the end of chromosome 4. Through variant investigations in that region we identified a deletion of about 20 kb encompassing 9 genes. By complementation analysis we confirmed that one of the deleted genes VTC2 is the causal gene responsible for the low NPQ. Loss of VTC2 decreased NPQ particularly in old leaves with young leaves being only slightly affected. [...]