Study On Physiological, Biochemical And Molecular Mechanism Of Rooting To Populus Tremula×P.tremuloides

Cutting is the main form of vegetative reproduction of forest, and the key to breed quality varieties is rooting technique. For some forestry species with roots hard, low rooting cutting rate is bottleneck that restricted use of cuttings for clonal forestry development. So far the research on forests rooting have some progresses in the physiological and biochemical levels, but rooting is a complex biological process, and the study only from the physiological and biochemical level can not reveal the underlying mechanism, so we need the comprehensive study of mechanism of rooting from many aspects.Based on Populus tremula×P.tremuloides micro-cutting technology, rooting anatomical, physiological, biochemical and molecular mechanism were studied. The investigation of molecular mechanism was through on European and American roots in the different periods of Solexa genome sequencing, bioinformatics analysis, analysis of the molecular mechanism of rooting, finding related genes and their functions in the process of cutting and adventitious rooting. It also provided the scientific basis for the breeding using genetic engineering by exploring the correlation between rooting related genes and phenotypic. The research has important scientific significance. The result of this paper is as follows:1 Morphological and anatomical studies of rooting:Europe and America hybrid aspen belong to cortex inducted rooting, and root primordia was originated from the phloem parenchyma cells. The callus formation was not directly related to the occurrence of adventitious roots cutting, and the developed cutting of callus was rooted no longer.2 Research on physiology of rooting process:IAA, ABA, ZR, GA3 played an important role in the stage of induction and adventitious root primordia elongation for hybrid aspen. IAA, ZR, GA3 were involved in the collaborative formation process of adventitious roots. In the stage of root primordial induction and formation, activities of PPO, POD, IAAO were increased, while in the stage of adventitious root elongation, activities of PPO and POD were decreased. IAAO activity maintained in a high level. Soluble sugar and protein content of hybrid aspen were decreased in the process of rooting in the total.3 The molecular mechanism of cutting rooting:Adventitious root development of cuttings is a complex biological process. Through the Europe and America hybrid aspen rooting during the two periods of material conducte Solexa genome sequencing,21508 differential expression genes were selected referred to digital detection of differential gene expression profiles. Based on populus trichocarpa genome database and integrated a number of public databases in molecular biology resources, the selection of aspen to the differentially expressed genes was studied with related to biological functional annotation. Furthermore, some of the significant genes for the development of adventitious root cuttings were cited and analyzed. The genes expressed differentially were related to metabolism, signaling pathways, material transport, resistance-related, growth and development, energy metabolism, cell cycle genes and so on by conducting GO and Pathway analysis of enriched significantly. Our study also received a large number of new gene which had not been reported, indicating that the functions of many genes during the formation of adventitious roots for hybrid aspen cuttings were not clear. The research not only provided the basis for the adventitious roots of aspen clone genes, but also lay the foundation for further development of molecular biology of adventitious root cuttings.