Hydrogen sulfide is a novel gasotransmitter with pivotal role in regulating lateral root formation in plants.

Hydrogen sulfide (H 2S), the third gasotransmitter after nitric oxide (NO) and carbon monoxide (CO), is a critical neuromodulator in the pathogenesis of various diseases from neurodegenerative diseases to diabetes or heart failure. The crosstalk between NO and H 2S has been well established in mammalian physiology. In planta, NO is demonstrated to regulate lateral root formation by acting downstream of auxin. The recent reports revealed that H 2S is a novel inducer of lateral root (LR) formation by stimulating the expression of cell cycle regulatory genes (CCRGs), acting similarly with NO, CO, and IAA. Interestingly, during the initiation of lateral root primordia, IAA is a potent inducer of endogenous H 2S and CO, which is produced by L-cysteine desulfhydrase (LCD) and heme oxygenase-1 (HO-1), respectively. The increasing evidences suggest that H 2S-promoted LR growth is dependent on the endogenous production of CO. In addition, our results indicate that the H 2S signaling in the regulation of LR formation can be associated to NO and Ca 2+. In this addendum, we advanced a proposed schematic model for H 2S-mediated signaling pathway of plant LR development.