The metabolic constituent and rooting-related enzymes responses of marigold explants to hydrogen gas during adventitious root development

Recent evidence suggests that hydrogen gas is involved in multiple physiological process in plants. However, the physiological mechanism of hydrogen gas on adventitious rooting is largely unknown. In this report, marigold (Tagetes erecta L.) was used to determine the effect of hydrogen gas on physiological changes during adventitious root development. The results showed that 50% hydrogen-rich water significantly increased root number and length of marigold explants. Hydrogen-rich water treatment provoked a significant reduction of stomatal aperture which might be associated with the increase of relative water content. Hydrogen-rich water decreased electrolyte leakage during adventitious rooting. The content of water-soluble carbohydrate, starch and soluble protein were higher in normal water-treated controls than in hydrogen-rich water-treated explants. Compared with the control, the application of hydrogen-rich water increased peroxidases, polyphenol oxidase and indoleacetic acid oxidase activity. Results indicated that hydrogen gas promotes adventitious root development through the increase of relative water content, metabolic constituents, rooting-related enzymes and simultaneously keeping cell membrane integrity.