Brassinosteroids is involved in methane-induced adventitious root formation via inducing cell wall relaxation in marigold

Background: Methane (CH4) and brassinosteroids (BRs) are important signaling molecules involved in a variety of biological processes in plants.Results: Here, marigold (Tagetes erecta L. 'Marvel') was used to investigate the role and relationship between CH4 and BRs during adventitious root (AR) formation. The results showed a dose-dependent effect of CH4 and BRs on rooting, with the greatest biological effects of methane-rich water (MRW, CH4 donor) and 2,4-epibrassinolide (EBL) at 20% and 1 mu mol L- 1, respectively. The positive effect of MRW on AR formation was blocked by brassinoazole (Brz, a synthetic inhibitor of EBL), indicating that BRs might be involved in MRW-regulated AR formation. MRW promoted EBL accumulation during rooting by up-regulating the content of campestanol (CN), cathasterone (CT), and castasterone (CS) and the activity of Steroid 5 alpha-reductase (DET2), 22 alpha-hydroxylase (DWF4), and BR-6-oxidase (BR6ox), indicating that CH4 could induce endogenous brassinolide (BR) production during rooting. Further results showed that MRW and EBL significantly down-regulated the content of cellulose, hemicellulose and lignin during rooting and significantly up-regulated the hydrolase activity, i.e. cmcase, xylanase and laccase. In addition, MRW and EBL also significantly promoted the activity of two major cell wall relaxing factors, xyloglucan endotransglucosylase/hydrolase (XTH) and peroxidase, which in turn promoted AR formation. While, Brz inhibited the role of MRW on these substances.Conclusions: BR might be involved in CH4-promoted AR formation by increasing cell wall relaxation.

Automated summary

Methane and brassinosteroids play important roles in adventitious root formation in marigold. Methane promotes the production of endogenous brassinolide and increases cell wall relaxation, leading to enhanced adventitious root formation. These findings provide insights into the signaling pathways involved in adventitious root development.