ERN1 and infection: As described by Chen et al. (2015), a core set of M. truncatula genes such as ERN1/2, NSP2, and several NF-Y genes are playing a central role in plant cell infection by rhizobia, both early (i.e., root hair cell infection) and late (i.e., nodule cell infection) during the nodulation process (Chen et al., 2015).