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

Abstract

Key message: Pharmacological and molecular evidence reveals a novel role of methane (CH 4 ) gas in root organogenesis, the induction of lateral root (LR) formation, and this response might require hydrogen peroxide (H 2 O 2 ) synthesis. Abstract: Although plants can produce CH 4 and release this to atmosphere, the beneficial role(s) of CH 4 are not fully elucidated. In this study, the fumigation with CH 4 not only increased NADPH oxidase activity and H 2 O 2 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 4 were sensitive to the removal of endogenous H 2 O 2 with dimethylthiourea (DMTU; a membrane-permeable scavenger of H 2 O 2 ), suggesting the hypothesis that CH 4 ’s effect on LR formation could be mediated by endogenous H 2 O 2 . Diphenylene iodonium (DPI) inhibition of the H 2 O 2 generating enzyme NADPH oxidase attenuated H 2 O 2 synthesis and impaired LR formation in response to CH 4 , confirming the requirement of NADPH oxidase-dependent H 2 O 2 . Meanwhile, the alterations of endogenous H 2 O 2 concentrations failed to influence CH 4 production in tomato seedlings. Molecular evidence revealed that CH 4 -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 H 2 O 2 synthesis in CH 4 -triggered tomato LR formation, partially via the regulation of cell cycle regulatory genes, miRNA-, and tasiRNA-modulated gene expression.