Poster: Secondary metabolism

Abs # 274: Tocopherol and carotenoid QTLs in Arabidopsis thaliana

Presenter:	Gilliland, Laura U, gillil11@msu.edu
Authors	Gilliland, Laura U (A)   Hemming, Cori A (A)   Magallanes-Lundback, Maria  (A)   Sattler, Scott  (A)   DellaPenna, Dean  (A)
Affiliations:	(A): Department of Biochemistry and Molecular Biology, Michigan State University

Plants contain a variety of safety mechanisms to limit the production of reactive oxygen species (ROS) or to rapidly detoxify ROS produced and limit the damage they cause. In plants, tocopherols act as physiochemical stabilizers of membranes rich in polyunsaturated fatty acids, physical quenchers of singlet oxygen (¹O₂), chemical scavengers of reactive oxygen species, and chain-breaking antioxidants during lipid oxidation. The health benefits of tocopherols (collectively known as the essential nutrient vitamin E) include maintenance of healthy neurological, muscular, immune, and reproductive systems. Carotenoids are accessory light harvesting pigments that can protect the reaction center from photodamage by directing excess energy away from the sensitive photosystems. Carotenoids, particularly lutein, the most abundant carotenoid in seeds, protect against cancer, heart disease, and macular degeneration. While most genes in the tocopherol and carotenoid synthesis pathways are known, novel genes that influence levels of these antioxidants or key regulatory elements of known genes may still be unidentified. We are utilizing the untapped genetic variation between Arabidopsis ecotypes to identify these genes. Quantitative trait loci (QTL) analysis of two sets of recombinant inbred lines has identified several distinct QTLs affecting tocopherol and lutein levels in seeds. We are fine mapping the underlying genes responsible for a QTL elevating γ-tocopherol levels on chromosome 3 and two QTLs affecting lutein levels using near isogenic lines. The identification of genes affecting the level of these antioxidants in Arabidopsis will further our knowledge of the regulation of enzymatic pathways and have ramifications for traditional crop breeding and metabolic engineering.