Synthetic auxin, indole-3-butyric acid (IBA), effectively promoted the rooting in Cinnamomum kanehirae cuttings. The easy-to-root genotype, H107, responded to IBA much earlier than the difficult-to-root genotype, L41. On day 5, the POD activity significantly decreased in the IBA-treated tissues as compared with the control. Similar phenomenon was observed in extract of L41 genotype showing that IBA inhibited POD activity. In addition, the variation in POD activity corresponds to an inverse variation in the concentration of free IAA. The levels of IAA in H107 genotype increased dramatically in IBA-treated tissues on day 5; while, in L41 genotype, the raise of IAA in IBA-treated tissues was observed on day 20. Moreover, the lignin content in IBA-treated H107 cuttings decreased is quite correlated with the decline of the POD activity; yet the lignin content in L41 genotype cuttings was almost unchanged. Hence, we suggest that the inhibition on POD may lead to the redifferentiation processes induced by IBA, then produce the new root primordia during the formation of adventitious roots.

Auxin can induce adventitious rooting. Synthetic auxin, indole-3-butyric acid (IBA), effectively promoted the rooting in Cinnamomum kanehirae. The peroxidase (POX) activity significantly decreased in the IBA-treated tissues as compared with the control. Hence, I suggest that the inhibition on POX activity may lead to the redifferentiation processes induced by IBA, which produces the new root primordia during the formation of adventitious roots. On this investigation, I cloned POX cDNA from the young roots. Degenerate primers were designed from the conservative regions of other published POX to amplify the expectant DNA fragment. Full-length cDNA of the POX gene designated CKPX1 and CKPX3 were cloned by the method of 5'and 3' RACE. The deduced amino acid of CKPX1 and CKPX3 were compared with the previously reported POX and showed between 40% and 60% identity with those plant species. Further studies on the promoter elements of CKPX3 were found out that elements related to auxin response, lignification, pathogen invasion and stress response. The results suggest that CKPX3 may be involved in the regulate process of adventitious rooting and defense against pathogens and environment stress.

Auxin can induce adventitious rooting. Synthetic auxin, indole-3-butyric acid (IBA), effectively promoted the rooting in Cinnamomum kanehirae. In Cinnamomum kanehirae, there are high (H) and low (L) rooting cultivar. The peroxidase (POX) activity significantly decreased in the IBA-treated tissues as compared with the control. The inhibition on POX activity may lead to the redifferentiation processes induced by IBA. In this investigation, we cloned POX cDNA from the young roots. Degenerate primers were designed from the conservative regions of other published POXs to amplify the expectant DNA fragment. We found that the H and L line have similar genes (>99%). The Full-length cDNA of the POX genes were cloned by the method of 5'and 3' Rapid Amplification of cDNA Ends (RACE). The deduced amino acid were compared with the previously reported POX and showed between 40% and 70% identity with other plant POXs. Further studies on the promoter elements of POX in High-rooting cultivar and Low-rooting line show that some elements are related to auxin response, lignification, pathogen invasion and stress response. The regulatory elements of the POX gene in High-rooting line contain sugar repression responsiveness (SRS) elements that might repress the expression of POX gene, causing the lower POX activity.