NIN and infection: Probably, the most vital transcription factor that controls epidermal infection, cortical cell division and nodule number is NIN. nin mutants undergo excessive root hair curling in response to inoculation by Sinorhizobium, but are impaired in infection and do not show any cortical cell division (Marsh et al., 2007; Soyano et al., 2014; Yoro et al., 2014).