9723592 DellaPenna Carotenoids are integral components of plant photosystems and their compositions in photosynthetic membranes is remarkably conserved. In order to increase our understanding of carotenoid synthesis and function in plants, the work uses a molecular approach in Arabidopsis to define and disrupt the pathway and thereby modify carotenoid production in vivo. Two loci, responsible for the synthesis of lutein have been identified. In a comparison between wild type and mutant lines, the work will characterize the production and accumulation of carotenoids during growth and development, in response to various environmental perturbations, monitor pigment/ protein complex structure and composition, and measure the effect of altered pigment composition on photosynthetic parameters.