Objective Gibberellin (GAs) is an important plant hormone, which has a wide range of regulatory effects on plant growth and development. In this paper, the regulatory role of gibberellin in stem cambium in plant growth and development was studied, providing reference for elucidation of the transport and regulatory role of source active GAs in plants.

Method In this study, the content of active GAs in stem cambium was specifically down-regulated by transgenic method to explore its regulatory effect on the growth and development of plant stems, leaves and roots. On this basis, 35S:: PtGA20ox and 35S:: PtGA2ox1 transgenic tobacco strains were used as scions and rootstocks respectively for micrografting and application of external GAs, to explore the transport characteristics of endogenous and exogenous active GAs in tobacco.

Result The results showed that the content of GAs in the stem of PtGA2ox1 transgenic plants mediated by the specific promoter LMX5 in the stem cambium was significantly lower than that in the wild type, while there was no significant change in the content of GAs in the leaves and roots. By observing paraffin sections, we found that the decrease of GAs content in stem cambium significantly delayed the development of stem xylem and inhibited the growth of leaf and lateral root. The analysis of micrografting of different transgenic lines shows that the exogenous GAs can restore the phenotype caused by the lack of stem cambium GAs, while the endogenous active GAs cannot be transported freely or restore the phenotype.

Conclusion Stem cambium GAs content is not only an important role in the development of stem xylem, and development of the growth of leaves and adventitious roots also have regulation function, the method of using micro grafting reactive GAs is verified in transport mechanism in the tobacco, it has been clear about the GAs in the regulating plant tissue development, for the future GAs thus lay a foundation for the application in the trees.