The RAM produces all the tissues of the primary root by a highly defined pattern of cell divisions. Cells produced by the meristem, known as initials, undergo proliferative cell www.selleckchem.com/products/Cisplatin.html divisions as they are added to files of different cell types and their fate is determined by positional informa tion. The stem cell niche in the root is maintained by a small group of cells called the quiescent centre. the QC inhibits the division of surrounding Inhibitors,Modulators,Libraries cells and is generated and maintained by the accumulation of auxin via the PIN auxin efflux carriers. in Arabidopsis the genes are known to be necessary for QC forma tion. The interplay of auxin and cytokinin controls the size of the RAM, with the action of cytokinin impli cated Inhibitors,Modulators,Libraries in controlling the exit of cells from the root meris tem.

Several studies that characterise gene expression in the cells of the root meristem have been published. Studies in Arabidopsis have used green fluorescent protein labelled cell types and cell sorting to characterise gene expression by microarray, for specific cell types Inhibitors,Modulators,Libraries and in different zones of root development. A root tissue specific gene expression study has also been carried out in maize where the proximal meristem, QC and root cap were microdissected and gene expression was measured on Affymetrix rice genome arrays. However the root of model legume Medicago truncatula presents a notably different system for study of root development to that of Arabidopsis thaliana or maize. At a cellular level, the root of M. truncatula has a significantly different RAM to that of Arabidopsis.

Most legume roots, unlike the Arabidopsis root have a basic open root meristem. The difference between open and closed meristems is significant. in the open RAM, initials are not apparent indicating possible variations in the regulation cell division and differentia tion between the two types of RAM. Hamamoto et al. have shown that roots with an open meristem produce individual Inhibitors,Modulators,Libraries living border cells and more border Inhibitors,Modulators,Libraries cells than those with a closed meristem. Border cells are important for mycorrhizal and microbial interactions including the legume rhizobia symbiosis and environmental sens ing. In terms of root organogenesis, the most obvious differ ence between M. truncatula and other model plants and is the ability of M. truncatula to form indeterminate root nodules in association with rhizobia.

Nodulation shares several aspects of lateral root organogenesis with the advantage that it is inducible and the site of organogenesis is predictable. Root organogenesis is also inducible in M. truncatula in tissue culture with the addition of auxin 1 naphthaleneacetic acid to the tissue culture media. Root formation in culture is irreversible after 7 days on inhibitor MG132 NAA and does not require ethylene perception. Thus, the morphological differences between the M.