Projects

Glutathione (GSH) is an important and abundant reducing agent in plants. GSH is involved in tolerance and adaptation to environmental stresses, including drought, pollution and temperature extremes. The rate-limiting step in GSH production is catalyzed by gamma-glutamylcysteine synthetase (GCS). In Arabidopsis, two GSH-deficient mutants define a single locus, ROOT MERISTEMLESSI (RML1)/CADMIUM SENSITIVE2 (CAD2), encoding GCS. The rmll mutant contains 2% of wild-type GSH levels and although embryonic development is normal, on germination, rmll root cells fail to divide and consequently do not maintain the root meristem. In contrast, shoot development proceeds relatively normally. The rmll phenotype is rescued by exogenous GSH (but not other reductants) indicating the specific importance of GSH in root cell division. Moreover, wild type plants phenocopy rmll when depleted of GSH by a specific inhibitor of GCS, buthionine sulfoximine (BSO). In tobacco cell culture, BSO treatment causes a specific arrest in cell division at a Gl checkpoint during the cell cycle. These results show a clear link between cell cycle progression and GSH levels in cell cultures and in the root meristem.

Here we propose to analyse its nature and mechanism by

(a) establishing which known cell cycle genes respond to GSH levels,

(b) identifying novel genes that are affected by GSH levels by using micro arrays and

(c) analyzing the novel genes to find which are upstream regulators of cell cycle targets.

To achieve these aims we will use the specific GCS inhibitor, buthionine sulfoximine, to deplete GSH levels in the novel synchronizable MM1 and MM2d Arabidopsis cell lines in combination with the rmll and cad2mutants and examine gene expression. During this project the candidate will gain valuable scientific training (ingenomics, bioinformatics and cell biology) and professional training (through presentations and the host institution’s personal development )

Sources: European Commission