ERN1 and infection: Considering the effect of NIPK post-transcriptional gene silencing on infection and nodule formation, we evaluated whether the expression of early nodulation genes was affected by silencing of NIPK. As observed in Figure 7B, the induction of the ethylene response factor required for nodulation ERN1 (Middleton et al., 2007; Cerri et al., 2012) and Early Nodulin 40 (ENOD40; Crespi et al., 1994) was impaired in roots that express NIPK RNAi 1.