Arabidopsis mutants impaired in primary metabolism as tools to study retrograde signaling mechanisms

• Applicant: Dr. Rainer E. Häusler
• Subject Area: Plant Physiology
• Term: from 2007 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 29017492

Lesions in primary metabolism, i.e. by an impaired photoassimilate export from the chloroplast via the triose phosphate/phosphate translocator (TPT) in the light and in starch biosynthesis due to a knockout of ADPglucose pyrophosphorylase (AGD) in the Arabidopsis thaliana double mutant alleles adg1-1/tpt-1 or adg1-1/tpt-2, result in a disturbed acclimation to high light (HL) (i.e. the long term response [LTR]). Whereas under low light (LL) conditions, the double mutant lacks any significant growth or photosynthesis phenotype compared to wild-type or single mutant plants, exposure to HL leads to strong photoinhibition, an over-reduced stroma, a decline in the abundance of plastome-encoded PSII core proteins, grana hyperstacking, and a diminished LHCII phosphorylation. In LL to HL shift experiments, we have collected relevant data, including global expression profiles, during the ongoing funding period and will exploit these data to study retrograde redox signals as well as the role of the metabolic state, including free sugars, in retrograde signalling. Based on candidate genes specifically deregulated in adg1-1/tpt-2 during LL to HL shift experiments, a major focus will be on the identification of new transcriptional regulators and the confirmation of already known regulatory elements. With the aid of phenocopy mutants of adg1-1/tpt-2, we will extend our search for elements involved in retrograde redox signalling. In a second part of the project, we will focus on the assessment of metabolic profiles in our mutant lines during LL to HL shift experiments and hope to identify key metabolites relevant to acclimation. A third focus will be the identification of membrane proteins of the inner envelope involved in the transduction of redox signals.

• DFG Programme: Research Units
• Subproject of: FOR 804: Retrograde Signalling in Plants
• Participating Person: Professor Dr. Ulf-Ingo Flügge