Hydrogen Peroxide Is Involved in -Cyclodextrin-hemin Complex-Induced Lateral Root Formation in Tomato Seedlings.

Although previous results showed that -cyclodextrin-hemin complex (-CDH) could induce tomato lateral root (LR) formation, the corresponding downstream messengers are still not fully understood. In this report, similar to the inducing effects of exogenously applied hydrogen peroxide (HO), we discovered that -CDH elicited transcript upregulation, endogenous HO accumulation, and thereafter tomato LR development. Above responses were sensitive to dimethylthiourea (DMTU) and ascorbic acid (AsA), two membrane-permeable scavengers of HO, showing that accumulation of HO and LR formation were significantly blocked. The test with diphenyleneiodonium (DPI; the inhibitor of NADPH oxidase) revealed that HO mainly produced by NADPH oxidase, might be involved in LR formation triggered by -CDH. qPCR combined with pharmacological and anatomical analyses showed that -CDH-modulated several marker genes responsible for LR formation, such as , and (four cell cycle regulatory genes), and (two auxin signaling genes), (an auxin influx carrier), (encoding a member of the Aux/IAA protein family), and (two auxin efflux carriers), , and genes (two reactive oxygen species-associated genes and one LR formation-related gene), were causally related to above HO signaling. Particularly, representative proteins related to HO metabolism and lateral rooting, were specifically induced in -CDH-treated tomato seedlings. Overall, the results clearly suggested a vital role of HO in the -CDH-induced tomato LR formation, and -CDH-elicited HO-related target proteins responsible for LR formation might be, at least partially, regulated at transcriptional and translational levels.