L-Cysteine Desulfhydrase-dependent Hydrogen Sulfide is Required for Methane-induced Lateral Root Formation

Methane-triggered lateral root formation is not only a universal event, but also dependent on L-cysteine desulfhydrase-dependent hydrogen sulfide signaling. Whether or how methane (CH) triggers lateral root (LR) formation has not been elucidated. In this report, CH induction of lateral rooting and the role of hydrogen sulfide (HS) were dissected in tomato and Arabidopsis by using physiological, anatomical, molecular, and genetic approaches. First, we discovered that CH induction of lateral rooting is a universal event. Exogenously applied CH not only triggered tomato lateral rooting, but also increased activities of L-cysteine desulfhydrase (DES; a major synthetic enzyme of HS) and induced endogenous HS production, and contrasting responses were observed in the presence of hypotaurine (HT; a scavenger of HS) or DL-propargylglycine (PAG; an inhibitor of DES) alone. CH-triggered lateral rooting were sensitive to the inhibition of endogenous HS with HT or PAG. The changes in the transcripts of representative cell cycle regulatory genes, miRNA and its target genes were matched with above phenotypes. In the presence of CH, Arabidopsis mutant Atdes1 exhibited defects in lateral rooting, compared with the wild-type. Molecular evidence showed that the transcriptional profiles of representative target genes modulated by CH in wild-type plants were impaired in Atdes1 mutant. Overall, our data demonstrate the main branch of the DES-dependent HS signaling cascade in CH-triggered LR formation.