Profiling Gene Expression in Germinating Roots.

Based on previously developed solid-phase gene extraction (SPGE) we examined the mRNA profile in primary roots of seedlings for highly expressed genes like (actin7), (tubulin1), (ubiquitin), and low expressed (glucokinase) during the first day post-germination. The assessment was based on the mRNA load of the SPGE probe of about 2.1 ng. The number of copies of the investigated genes changed spatially along the length of primary roots. The expression level of all genes differed significantly at each sample position. Among the examined genes expression was most even along the root. was highest at the tip and root-shoot junction (RS). and showed a basipetal gradient. The temporal expression of was highest in the MZ 9 h after primary root emergence and higher than at any other sample position. Expressions of in EZ and RS increased gradually over time. SPGE extraction is the result of oligo-dT and oligo-dA hybridization and the results illustrate that SPGE can be used for gene expression profiling at high spatial and temporal resolution. SPGE needles can be used within two weeks when stored at 4 °C. Our data indicate that gene expression studies that are based on the entire root miss important differences in gene expression that SPGE is able to resolve for example growth adjustments during gravitropism.