Results and discussion The M. truncatula root meristem The M. truncatula RAM shows a characteristic basic open root meristem organisation. In the region where cells are dividing, it isnt possible to distinguish the initials amongst the tightly packed mass of new and Erlotinib cancer elon gating cells in the root tip. Our meristem section, 3 milli metres from the root tip, is comprised large group of undifferentiated cells, surrounded by some differentiated tissues including border cells, root cap and elongating cells that will form the vascular bundle, pericycle, endo dermis, cortex and epidermis. Our non meristematic sec tion, one centimetre adjacent to the meristem, only contains the characteristic root tissue layers. root hairs occur in this region, rhizobial infection and lateral root initiation occur in this zone.
These sections were chosen to correspond with earlier Inhibitors,Modulators,Libraries proteomic work on the Medi cago root meristem and because there are no described markers for specific cell types in the Medicago root meristem Inhibitors,Modulators,Libraries that could be used to create transgenic plants for a cell type analysis. To characterise the transcriptomes of the meristematic and non meristematic root of the M. truncatula we extracted RNA from the meristem and non meristematic zones from the roots of three independently grown sets of plants four days after germination. The three biological replicates were analysed using the Affymetrix Medicago genome array. An average of 51% of the over 52, 000 plant gene probes of the Medicago Genome Array GeneChip produced present calls when hybridised with biotin labelled cRNA from M.
truncatula roots consistent with early reports. Following nor malisation with GCRMA, we identified 324 transcripts that are greater that 2. 0 fold Inhibitors,Modulators,Libraries over expressed in the meris tem and 363 that are over expressed in the non meristem. The full data set has been deposited in the Gene Expres sion Omnibus database as accession Inhibitors,Modulators,Libraries GSE8115. the nor malised data set is available in additional file 1. Although our meristem sample is comprised of multiple cells types, Inhibitors,Modulators,Libraries including stem cells, elongating and differenti ating cells and some differentiated cell types, proteome and transcriptome data suggests that the material contains a significant proportion of stem cells. Previously we have shown with proteomic analysis that the root meristem accumulates significantly more actin and tubulin than non meristematic tissues, consistent with cell prolifera tion in the meristem.
The array data also shows that the transcript of the ortholog of the M. sativa cyclin A2, Medsa. cycA2. 2 is expressed greater than 2 fold in our meristematic root section. Cyclin A2 is important in the transition to DNA synthesis and replica tion phases of the cell cycle and is selleck destroyed as the cell moves into mitosis, in M. sativa Medsa. cycA2.