Genes differentially expressed in wild-type Medicago truncatula plants during nodulation

We used an Affymetrix oligonucleotide microarray consisting of 9,935 tentative consensus (TC)sequences, which are based on cDNA libraries (Mitra et al., 2004 [PMID:15220482]). We examined gene expression of wild-type M. truncatula plants after inoculation with wild-type S. meliloti at 1 d, 4 d, 7d, 14 d, and 21 d. We chose these time points because they span the range of development of the Rhizobium-legume symbiosis, from initiation of the interaction through nitrogen fixation. The gene expression data for the 1-day time point (Mitra et al., 2004 [PMID 15220482]) and the other time points was previously published (Starker el al., 2006 [PMID 16407449]). Three or five independent biological replicates were performed at each time point (1, 4, 7, 14 and 21 days after treatment) and each treatment (buffer and wild-type bacteria).