Poster: Photosynthesis

Abs # 319: Genome-scale RNA expression and metabolic profiling of high-light acclimation in wild-type and photoprotection mutants of Arabidopsis thaliana

Presenter:	Golan, Talila , tgolan@uclink.berkeley.edu
Authors	Golan, Talila  (A)   Lange, Bernd Markus  (B)   Ghassemian, Majid  (B)   Lutes, Jason  (B)   Zhu, Tong  (B)   Chang, Sherman  (B)   Niyogi, Niyogi K (A)
Affiliations:	(A): University Of California (B): Torrey Mesa Research Institute

Acclimation of plants to their light environment is necessary to optimize photosynthetic efficiency and overall plant health. The mechanisms of acclimation are numerous and range in response time from minutes (e.g. events within the light-harvesting complex) to days (e.g. alterations in leaf morphology). We exposed low-light (LL)-grown wild-type (WT) Arabidopsis thaliana plants and three photoprotection-deficient mutants to high light (HL) for a period of 10 days. We performed genome-scale RNA expression analysis as well as a comprehensive metabolic profiling on leaf samples taken prior to HL exposure, after 4 hours of HL treatment, and after 10 days of HL treatment. Gene expression results showed large changes in expression profile between each of the light treatments but only small changes between the WT and the photoprotection-deficient mutants. Differences between the mutants and the WT were seen, however, in the levels of certain metabolites. Expression of genes involved in primary carbon metabolism and sugar metabolism increased in response to HL, suggesting an overall increase in metabolic activity, but no major changes in steady-state sugar levels were seen. Enhancement of expression was seen also in genes of the flavonoid, carotenoid and tocopherol biosynthesis pathways, which was supported by the metabolic profile, indicating acclimation to conditions of higher photo-oxidative stress. We also observed specific changes in fatty acid and lipid metabolism genes, and an increase in the jasmonic acid synthesis pathway. The results and their relevance to HL acclimation will be discussed.