Poster: Metabolic Engineering

Abs # 1010: Functional characterization of AtTPS1 and its modulatory expressionexpression under abiotic stresses

Presenter:	Lee, Jee Hyun , jhyun313@snu.ac.kr
Authors	Lee, Jee Hyun  (A)   Lee, Kyung-Hoon  (A)   Kim, Jae Joon  (A)   Yang, Jin-Young  (A)   Jun, Sung-Soo  (A)   Hong, Young-Nam  (A)
Affiliations:	(A): Seoul National University

Trehalose, a disaccharide of two glucose units, is known as a stress protectant in microorganisms. It is synthesized by sequential action of TPS (trehalose-6-phosphate synthase) and TPP (trehalose-6-phosphate phosphatase) and is degraded by trehalase. However, it is rarely found in higher plants and its role is yet unknown. We have shown that transgenic tobacco plants producing trehalose exhibited improved tolerance against dehydration and high temperature. But minute amounts of trehalose detected in these transgenic plants suggest that it is not likely to act directly as osmoprotectants. Furthermore, morphological alterations and delayed senescence in transgenic plants might imply its some other role. Recently, 11 homologs of TPS were found in Arabidopsis by its genome project. Among those, AtTPS1 was the only functional homolog identified so far. To look into the role of trehalose in Arabidopsis, we examined AtTPS1 expression by nothern blot, RT-PCR, and histochemical analysis of AtTPS1::GUS plants. The results indicate that although of constitutive nature, AtTPS1 was differentially expressed in various tissues and in different developmental stages: AtTPS1 was more strongly expressed in stems and leaves on vascular bundle area. Furthermore, AtTPS1 was up-regulated by various abiotic stresses including drought, heat, chilling, salt, and wounding stresses. It was also up-regulated by sucrose treatment. The results, together with exhibition of enhanced tolerance against dehydration, heat and salt stresses in transgenic tobacco plants strongly suggest that trehalose may play a regulatory role under various environmental stresses.