Hydrogen peroxide is involved in hydrogen sulfide-induced lateral root formation in tomato seedlings.

BACKGROUND

Both hydrogen sulfide (HS) and hydrogen peroxide (HO) are separately regarded as a highly reactive molecule involved in root morphogenesis. In this report, corresponding causal link governing lateral root formation was investigated.

METHODS

By using pharmacological, anatomic, and molecular approaches, evidence presented here revealed the molecular mechanism underlying tomato lateral root development triggered by HS.

RESULTS

A HS donor sodium hydrosulfide (NaHS) triggered the accumulation of HO, the up-regulation of RBOH1 transcript, and thereafter tomato lateral root formation. Above responses were sensitive to the HO scavenger (dimethylthiourea; DMTU) and the inhibitor of NADPH oxidase (diphenylene idonium; DPI), showing that the accumulations of HO and increased RBOH1 transcript were respectively prevented. Lateral root primordial and lateral root formation were also impaired. Further molecular evidence revealed that HS-modulated gene expression of cell cycle regulatory genes, including up-regulation of SlCYCA2;1, SlCYCA3;1, and SlCDKA1, and the down-regulation of SlKRP2, were prevented by the co-treatment with DMTU or DPI. Above mentioned inducing phenotypes were consistent with the changes of lateral root formation-related microRNA transcripts: up-regulation of miR390a and miR160, and with the opposite tendencies of their target genes (encoding auxin response factors). Contrasting tendencies were observed when DMTU or DPI was added together. The occurrence of HS-mediated S-sulfhydration during above responses was preliminarily discovered.

CONCLUSIONS

Overall, these results suggested an important role of RBOH1-mediated HO in HS-elicited tomato lateral root development, and corresponding HS-target proteins regulated at transcriptional and post-translational levels.