The Cloning And Functional Analysis Of GA Receptor GID1 In Conifers

Gibberellin (GA) is an indispensable phytohormone in plant growth and development. And it is significant value for application on seeds germination and flower bud differentiation in conifers. GID1. (Gibberellin Insensitive Dwarf 1) is the soluble receptor protein in GA signaling pathway, which is a key factor of the activation of gibberellin effect. The genes encoding the GID1 proteins have been widely cloned in angiosperms, but the related research in conifers is still lagging behind. In order to separate and identify the GID1 homologous genes in conifers, speculate its function, we separated and identified the GID1 homologous gene in the whole genomes of pinus tabulaeformis in this study. And then, we got the transgenic arabidopsises of 355::PtGID1 using the method of agrobacterium infection. The phenotypic characters and seed germination of the transgenic plants and wild type have also been analyzed. The main results were as follows:1. Using the sequences of arabidopsis and rice GID1 proteins as the probes, run the BLAST in the reference transcriptome of p.tabulaeformis. Through the analysis of system development, we obtained only one GID1 orthologous gene in the whole p.tabulaeformis genome finally.2. Put the p.tabulaeformis GID1 genes as reference, we obtained the GID1 homologous gene in eight conifers via the homology cloning and BLAST. The sequences analysis showed that the sequence identities between p. tabulaeformis and Picea abies, Larix kaempferi were 91% and 86%, respectively. While compared with P. densiflora and p. sylvestris, the identity was up to 99% both. In eight conifers, the Ka/ks< 1, it indicated that there was pure selection in the evolution of GID1 gene. The domain and the key amino acid residues for GA binding and interacting with DELLA proteins were all conserved in eight conifers. These showed that in conifers the evolution of GID1 gene was very conservative.3. The GID1 gene expression pattern analysis in different tissues of Norway spruce and p.tabulaeformis showed that the gene was expressed in the cones and other organizations, and the variation range of expression was slight in two species. This suggested that the GID1 genes might be the constituted expression in conifers, and participated widely in the development process of these organizations.4. The phenotype observation of positive transgenic arabidopsis and wild type showed that the flowering time of the transgenic plants got ahead and the plant height was increased. This suggested that the PtGID1 gene can promote the plant growthment and development in Arabidopsis thaliana. Using the paclobutrazol (PAC) and GA3 treatment arabidopsis seeds, the results showed that the transgenic seed could germinate under the condition of low concentration of GA3. These showed that the PtGID1 gene can enhance the ability of feelings to GA3 in arabidopsis seed germination.The results lay the foundation for the research on molecular regulatory mechanism of GID1 gene in conifers growth and development.