The ROOT MERISTEMLESS1/CADMIUM SENSITIVE2 Gene Defines a Glutathione-Dependent Pathway Involved in Initiation and Maintenance of Cell Division during Postembryonic Root Development

Abstract

Activation of cell division in the root apical meristem after germination is essential for postembryonic root development. Arabidopsis plants homozygous for a mutation in the ROOT MERISTEMLESS1 (RML1) gene are unable to establish an active postembryonic meristem in the root apex. This mutation abolishes cell division in the root but not in the shoot. We report the molecular cloning of the RML1 gene, which encodes the first enzyme of glutathione (GSH) biosynthesis, gamma-glutamylcysteine synthetase, and which is allelic to CADMIUM SENSITIVE2. The phenotype of the rml1 mutant, which was also evident in the roots of wild-type Arabidopsis and tobacco treated with an inhibitor of GSH biosynthesis, could be relieved by applying GSH to rml1 seedlings. By using a synchronized tobacco cell suspension culture, we showed that the G(1)-to-S phase transition requires an adequate level of GSH. These observations suggest the existence of a GSH-dependent developmental pathway essential for initiation and maintenance of cell division during postembryonic root development.

Mitogen-Activated Protein Kinases and Reactive Oxygen Species Signaling in Plants

“…Kwak et al (2003) found that AtrbohF and AtrbohD/F double mutants have shorter roots compared to wild-type plants, and in glutathione-deficient root meristemless 1 mutants, roots fail to develop (Vernoux et al, 2000). In animals, the redox environment within the cell selectively regulates stress signaling through two MAPKKKs, MEKK1 versus ASK1, and is assumed to participate in the induction of apoptosis by oxidative stress.…”

Glutathione in plants: biosynthesis and physiological role in environmental stress tolerance

“…High GSH content was also correlated with regulation of leaf water content, which may indicate a role in controlling leaf rolling (Saruhan et al 2009). Glutathione supposedly has growth regulating functions, as elevation of the endogenous GSH level enhances cell division in the root meristematic region (Vernoux et al 2000); this elongation is an important morphological adaptation to drought.…”

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

“…Toxic xenobiotics, including herbicides, are conjugated with GSH by glutathione S-transferases and sequestered into the vacuole (Marrs, 1996). GSH is also involved in controlling cell size and root development by regulating the cell cycle (Vernoux et al, 2000;Xiang et al, 2001). GSH exists in high concentration in plant tissues and acts as a substrate for central biochemicals, particularly Cys, and Cys availability for protein synthesis and as a precursor for metabolites may be related to the rate of GSH degradation (Leustek et al, 2000).…”