Using this database we were able to identify statistically significant over represen tation of metabolic pathways in the meristematic and non meristematic root, shown in Table 2. Four metabolic pathways are significantly over represented in the meris tem and 10 are Dorsomorphin over represented in the non meristematic root. We also annotated the chip by comparing the data set with the Arabidopsis Gene Family Information database maintained by the Arabidopsis Information Resource. As of April 2007 the database contained 996 gene families and 8,331 genes. Using BLAST, we were able to classify 3159 Medicago probe sets into these families. Sixty nine and 71 of the differentially expressed probe sets from the meristem and non meristem respectively were classified in the gene families.
no families were signifi cantly over represented in either section. Finally, transcription Inhibitors,Modulators,Libraries factors on the Genome array were predicted by homology relationship based on the Database of Arabidopsis Transcription Factors. This analysis Inhibitors,Modulators,Libraries showed that 2932 probe sets on the Genome array have sequence homology to described plant TFs. Carbohydrate metabolism and cell wall biosynthesis The most notable metabolic difference between the mer istem and non meristematic root is carbon metabolism, carbon is fixed in the non meristematic root and sugars are metabolised in the meristem. PathExpress shows that transcripts of enzymes from the pathway of carbon metabolism are significantly over expressed in the non meristematic root.
they include glyceraldehyde 3 phos phate dehydrogenase PathExpress Inhibitors,Modulators,Libraries analysis also shows that transcripts of sugar metabolism enzymes are over expressed in the meristem, Inhibitors,Modulators,Libraries they include ADP glu cose pyrophosphorylase Beyond basic cellular energy needs, at least two processes in the root meristem have significant Inhibitors,Modulators,Libraries energy require ments. Gravitropism requires the accumulation of starch in the root cap, a component of our root meristem sam ple, in organelles known as statocytes. Arabidopsis plants that lack or have reduced accumulation of starch in the root have reduced response to gravity. gravity signal ling by statocytes and other signal transduction pathways leads the redistribution of auxin in the root cap in response to gravity. Another sink for sugar metabo lised in the meristem is cell wall biosynthesis and modifi cation, for a recent review of the biosynthesis of plant cell wall polysaccharides see Lerouxel et al. PathExpress analysis shows that enzymes implicated in the biosynthe sis of stilbene, coumarine and lignin are significantly over represented in both SB203580 HCC root sections. however in both instances the enzymes implicated are multiple isoforms of heme peroxidase, cytochrome P450 containing monoox ygenases and beta glucosidase.