NIN and infection: Target genes of NIN encode proteins such as NODULATION PECTATE LYASE (LjNPL), an enzyme that mediates cell wall degradation during infection thread initiation (Xie et al., 2012; Liu et al., 2019a); SCAR-Nodulation (LjSCARN), a component of the actin regulatory complex that promotes the formation of new actin filaments in root hairs during infection thread development (Qiu et al., 2015); and Nuclear Factor-YA1 (LjNF-YA1/MtNF-YA1), a transcription factor that promotes cortical cell division for nodule organogenesis (Combier et al., 2006; Soyano et al., 2013).