Abstract

Cellular redox homeostasis is considered to play an important role in the regulation of the plant cell cycle but there is little information on the precise functions of key redox metabolites such as ascorbate, glutathione and pyridine nucleotides in this process. In this seminar, I will show how the intracellular redox state was modulated during the growth cycle and discuss the interplay between the major redox pyridine nucleotides, glutathione and ascorbate pools (Pellny et al., 2009). Evidence of similarities in the redox control of cell proliferation in animals and plants are provided, particularly glutathione recruitment into the nucleus early in the cell proliferation, which appears to be important in the control of progression through the cell cycle in both kingdoms. GSH accumulation in the nucleus is triggered in Arabidopsis cells in culture by treatments that synchronize cells at G1/S as identified by flow cytometry and marker transcripts. GSH recruitment into the nucleus has marked effects on metabolism and signaling in the cytoplasm, chloroplasts and nucleus. For example, a comparison of the GSH :nuc and GSH :cyt transcriptomes revealed that significant decreases in transcripts associated with oxidative signaling and stress tolerance occurred when GSH was localized in the nucleus. The relationships between the intracellular glutathione pools, poly (ADP-ribose) polymerase (PARP) activities and the abundance of PARP1 and PARP2 mRNAs, will be discussed in terms of the regulation of growth and defence.

Reference : Pellny TK, Locato V, Diaz Vivancos P, Markovic J, De Gara L et al., (2009) Pyridine nucleotide cycling and control of intracellular redox state in relation to poly (ADP-ribose) polymerase activity and nuclear localisation of glutathione during exponential growth of Arabidopsis cells in culture. Molecular Plant 2: 442-456.