SUMMARYCellular redox homeostasis and signalling are important in progression of the eukaryotic cell cycle. In animals, the low-molecular-weight thiol tripeptide glutathione (GSH) is recruited into the nucleus early in the cell proliferation cycle. To determine whether a similar process occurs in plants, we studied cell proliferation in Arabidopsis thaliana. We show that GSH co-localizes with nuclear DNA during the proliferation of A. thaliana cells in culture. Moreover, GSH localization in the nucleus was observed in dividing pericycle cells of the lateral root meristem. There was pronounced accumulation of GSH in the nucleus at points in the growth cycle at which a high percentage of the cells were in G 1 phase, as identified by flow cytometry and marker transcripts. Recruitment of GSH into the nucleus led to a high abundance of GSH in the nucleus (GSHn) and severe depletion of the cytoplasmic GSH pool (GSHc). Sequestration of GSH in the nucleus was accompanied by significant decreases in transcripts associated with oxidative signalling and stress tolerance, and an increase in the abundance of hydrogen peroxide, an effect that was enhanced when the dividing cells were treated with salicylic acid. Total cellular GSH and the abundance of GSH1 and GSH2 transcripts increased after the initial recruitment of GSH into the nucleus. We conclude that GSH recruitment into the nucleus during cell proliferation has a profound effect on the whole-cell redox state. High GSHn levels trigger redox adjustments in the cytoplasm, favouring decreased oxidative signalling and enhanced GSH synthesis.

Reduced glutathione (GSH) is considered to exert a strong influence on cellular redox homeostasis and to regulate gene expression, but these processes remain poorly characterized. Severe GSH depletion specifically inhibited root meristem development, while low root GSH levels decreased lateral root densities. The redox potential of the nucleus and cytosol of Arabidopsis thaliana roots determined using roGFP probes was between -300 and -320 mV. Growth in the presence of the GSH-synthesis inhibitor buthionine sulfoximine (BSO) increased the nuclear and cytosolic redox potentials to approximately -260 mV. GSH-responsive genes including transcription factors (SPATULA, MYB15, MYB75), proteins involved in cell division, redox regulation (glutaredoxinS17, thioredoxins, ACHT5 and TH8) and auxin signalling (HECATE), were identified in the GSH-deficient root meristemless 1-1 (rml1-1) mutant, and in other GSH-synthesis mutants (rax1-1, cad2-1, pad2-1) as well as in the wild type following the addition of BSO. Inhibition of auxin transport had no effect on organ GSH levels, but exogenous auxin decreased the root GSH pool. We conclude that GSH depletion significantly increases the redox potentials of the nucleus and cytosol, and causes arrest of the cell cycle in roots but not shoots, with accompanying transcript changes linked to altered hormone responses, but not oxidative stress.

Hydropower energy is a clean alternative energy that has less impact on global climate change than fossil energy. However, the subsequent displacement and resettlement caused by dam construction is a global challenge perplexing the displaced population and the stability of the local socio-economic system. Without proper reconstruction and rehabilitation, the resettlers were highly risked in impoverishment. The Chinese government has formulated and implemented the post-relocation support (PReS) policy for reservoir resettlement and has continuously supported the resettlers to improve their livelihoods and socio-economic conditions since 2006. This paper focus on the 20 years dimension before and after policy formation, tests the variation of resettlers’ livelihood capital and explores the effectiveness of the PReS policy and its blank spots based on a survey of 360 affected households by three big hydroelectric dams in China. The results show that reservoir resettlers would have caused the overall decline of resettlers’ livelihood capital. The prominent problem is that the reduction of land resources and population relocation leads to the changes of resettlers’ livelihood diversification and lifestyle change, which puts forward new requirements for the improvement of job skills and personal capability; the policy plays a significant role in rapidly improving the social, economic, and physical assets of resettlers in the early stage of reservoir resettlement; from the time scale of 15 years of policy implementation, the resettlement policy has an obvious slow-release effect on making up for the improvement of natural resources development and human capital; there are still blank spots in the current resettlement policy. Therefore, it is necessary to adjust and extend the policy for specific groups of people.