Abstract: In order to investigate the mechanism of IBA-induced adventitious rooting from hypocotyl cuttings of pepper（Capsicum annuum L.），we detected the process of adventitious rooting，contents of carbohydrates，and expression of genes related to adventitious root formation. The results indicated that exogenous IBA could regulate the adventitious root number in a dose-dependent manner. Compared with the control without IBA，cuttings treated with 150 μmol ? L-1 IBA showed maximum adventitious root number，rooting zone length and average root length. In addition，the expression levels of CaARL1 and CaCycB1 increased greatly after 150 μmol ? L-1 IBA treatment. Adventitious root primordia could occur at both basal and upper segments of hypocotyl cuttings treated with IBA，thus the length of rooting zone was greatly increased. Furthermore，after IBA treatment，the expression levels of CaCWI and CaSTP genes，contents of carbohydrates and activity of cell wall invertase were significantly increased. In conclusion，appropriate concentration of IBA treatment could enhance the accumulation and transformation of carbohydrates at the rooting zone，thereby promoting adventitious root formation on the hypocotyls of pepper seedlings.

Key words: pepper, hypocotyl, adventitious root, IBA, carbohydrate