Hydrogen peroxide is involved in methane-induced tomato lateral root formation.

Pharmacological and molecular evidence reveals a novel role of methane (CH) gas in root organogenesis, the induction of lateral root (LR) formation, and this response might require hydrogen peroxide (HO) synthesis. Although plants can produce CH and release this to atmosphere, the beneficial role(s) of CH are not fully elucidated. In this study, the fumigation with CH not only increased NADPH oxidase activity and HO production, but also induced tomato lateral root primordial formation and thereafter LR development. However, exogenously applied argon and nitrogen failed to influence LR formation. Above responses triggered by CH were sensitive to the removal of endogenous HO with dimethylthiourea (DMTU; a membrane-permeable scavenger of HO), suggesting the hypothesis that CH's effect on LR formation could be mediated by endogenous HO. Diphenylene iodonium (DPI) inhibition of the HO generating enzyme NADPH oxidase attenuated HO synthesis and impaired LR formation in response to CH, confirming the requirement of NADPH oxidase-dependent HO. Meanwhile, the alterations of endogenous HO concentrations failed to influence CH production in tomato seedlings. Molecular evidence revealed that CH-induced SlCDKA1, SlCYCA2;1, and SlCYCA3;1 transcripts, and -decreased SlKRP2 mRNA were impaired by DMTU or DPI. Contrasting changes in LR formation-related miR390a and miR160 transcripts and their target genes, including SlARF4 and SlARF16, were observed. Together, our pharmacological and molecular evidence suggested the requirement of HO synthesis in CH-triggered tomato LR formation, partially via the regulation of cell cycle regulatory genes, miRNA-, and tasiRNA-modulated gene expression.