The depletion of endogenous auxin by NPA is considered as a useful tool to gain a good insight into the signaling transduction pathways responsible for lateral root formation (Casimiro et al., 2001). The crosstalk between endogenous HO-1/CO and H2S during adventitious rooting was previously proposed (Lin et al., 2012). In this context, we extended our former observations, demonstrating that NaHS is able to boost the induction of lateral root formation in auxin-depleted tomato seedlings. Most importantly, we further revealed that a linearity may exist in DES-mediated H2S signaling downstream of auxin to trigger lateral root formation by the modulation of cell cycle regulatory genes.