The role of the arabidopsis thaliana TREHALOSE 6-PHOSPATE SYNTHASE 5(AtTPS5) in plant stress response

Dietrich, Sabine; Usadel, Björn (Thesis advisor); van Dongen, Joost Thomas (Thesis advisor)

Aachen (2020)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2020


Trehalose 6-phosphate (T6P) is a plant metabolite, which has been shown to be importantin carbohydrate metabolism, development and abscisic acid (ABA) signaling. It is synthesized by the enzyme T6P synthase (TPS) which belongs to a gene family in Arabidopsis thaliana (Arabidopsis), which consists of 11 members, subdivided into two classes: class I (AtTPS1-4) and class II (AtTPS5-11). To date, enzymatic activity has only been reproducibly demonstrated for AtTPS1, 2 and 4, and the role of class II TPSs remain still elusive. This work focuses on unraveling the role of the T6P SYNTHASE5 (AtTPS5) in Arabidopsis. It could be shown, that AtTPS5 is involved in plants stress responses. A RNA Sequencing analysis of an Attps5 knockout mutant followed by an over representative analysis (ORA) revealed the differential expression of various genes involved in stress responses compared to wild type. In wild type plants, AtTPS5 expression was downregulated by isoxaben treatment and high NaCl concentrations.Additionally salt and drought stress experiments revealed an enhanced tolerance of tps5 mutants, which was accompanied, in the case of salt stress, by increased ABA levels. A pathogen infection assay also reveled a higher resistance against the plant pathogen Pseudomonas syringae pv. tomato DC3000 (P. syringae). A subcellular localization study indicated that AtTPS5 is located in the cytosol. Putative AtTPS5-interacting proteins were identified by yeast-2-hybrid and confirmed by bimolecular fluorescence complementation (BiFC) assay. These interacting proteins are: a PARVULIN-TYPEPEPTIDYL-PROLYL ISOMERASE (AtPIN2), which is likely involved in protein folding, CAROTENOID CLEAVAGE DIOXYGENASE 1 (AtCCD1) and N-MYCDOWNREGULATED-like2 (AtNDL2), which is a transcriptional activator of the early stress response mediator AtZAT12. In this work possible functions of AtTPS5, focused on plant stress response, are discussed.