Studies On Inheritance Of Recessive Tall Mutation And Function Of Transcription Factor Rdreb1 Gene In Rice (Oryza Sativa L.)

The rice is one of most important grain crops in the world. The genetic research of rice played an important contribution to increase rice production for a long time. The semi-dwarf genes have been used in rice breeding for selecting semi-dwarf varieties. The discovery of recessive tall mutation has provided a way to resolve F1 plant height problem in Indica-japonica hybrid rice. In order to adapt to the inconstant environments, it is required to selective the rice varieties with stresses resistance. The research of environmental stresses response has become the "hot point" in plant molecular biology. The allelic relationship between recessive elongated uppermost internode mutants and semi-dwarf varieties and cloning and function of transcription factor RdreBlb have been studied in this thesis. The main results were summarized as follow.1. Using recessive tall mutants (Grlc, 02428h) crossed with normal tall varieties including non-allelic semi-dwarf genes for investigating allelic relationship among various semi-dwarf genes, normal tall gene and recessive tall gene in rice. The results from F1 and F2 generation indicated that elongated uppermost internode gene (eui) controlled the recessive tall character. In addition, recessive tall mutants carried a common semi-dwarf genes sd-1, which was non-allelic to eui gene. The genotype of recessive tall mutants and normal tall for plant height was euieuisd-lsd-1 and EuiEuiSd-lSd-1, respectively, eui and sd-1 genes belonged to non-allelic loci genes. F2 segregation ratio of recessive tall hybridized to various semi-dwarf varieties with the same sd-1 gene showed a good fit to 3 semidwarfs: 1 tall and appeared segregation of gene eui. It appeared the model of singlelocus inheritance with eui recessive. However, some segregation ratio of F2 population showed interaction of 3 loci genes including eui and two non-allelic semi-dwarf genes in the crosses of recessive tall mutants with semi-dwarf varieties other than sd-1 gene. The F2 segregation ratio of 13 tall: 3 semi-dwarfs was resulted from the crosses of normal tall with recessive tall. Two recessive tall mutants carried the same eui and sd-1 genes.The elongated uppermost internode gene eui was transferred to restorer lines of hybrid rice by multiple backcrosses. The test crosses results for restorer lines with eui gene showed all F1 plants appearing semi-dwarf in plant height. The restorer lines carried eui gene have not negative effect on the heading date and several grain yield characters comparing with normal restorer lines in F1 generation. It discussed the application of eui gene in Indica-japonica hybrid rice breeding. One of the ways is to transfer the eui and wide compatibility genes to sterile lines of hybrid rice at the same time. The eui gene would cause better exertion of panicles in sterile lines. The hybrid of Indica or Japonica rice parents crossed with these modified sterile lines without any limitation would result in semi-dwarf and complete fertile in F1 generation. The heterosis of Indica and Japonica would be utilized through the traditional three lines ways in hybrid rice.2. Plant grows in an inconstant environment that frequently imposes constrains on growth and development of plants. The adaptive environments have protected the plant for growth and development normally. However, the adverse environment stresses can result in injure or death of plants because they cannot move by themselves. Drought, high salinity and low temperature are commonly adverse environmental conditions that affect the growth of plants and the productivity of crops. All of these environmental stresses are also called water stress. A number of genes have been reported to respond water stress in various species. The functions of some gene products have played a role in directly protecting the cells from water deficit. Most of drought- and cold stress-inducible genes that have been studied to date are also induced at transcriptional level. Genes induced during water-stress conditions are thought to function not only in protecting cells...