Three of the 19 RNS pathway genes were found to be universally nodule-enhanced: SYMREM (Lefebvre et al., 2010), a remorin that is known to interact with NFR1, in the most upstream portion of the RNS pathway; NIN (Schauser et al., 1999), a key transcription factor that is one of the more downstream RNS pathway genes required for nodule organogenesis; and RPG (Arrighi et al., 2008), a gene required for the proper growth and regulation of the infection thread that is key to the establishment of RNS in M.truncatula (Table 2). This evidence concerns the gene NIN and infection.