Nodulation gene expression patterns. Expression patterns (as Z-scores) of Pv homologs of genes involved in nodulation and symbiosis identified in Lotus japonicus, Medicago truncatula, and Glycine max. Red indicates a positive Z-score while blue indicates a negative Z-score. Genes common to both symbiotic nitrogen fixation and mycorrhizal symbiosis are denoted with an asterisk (*). See Table 1 for tissue descriptions.