Mapping Of A Dwarf And Narrow Leaf Mutant And Function Analysis Of Senescence And Male Sterility1(SMS1) Gene In Rice (Oryza Sativa L.)

A dwarf and narrow leaf (dnl1) mutant was isolated by ethylmethylsulfonate (EMS) treating for a japonica rice variety Xiushui09dry seeds, it could be genetically stable after several selfing. In this study, we have analysed the phenotype and genetic characteristic, mapped the gene of the dnl1mutant. Meanwhile, the reason of formation of dwarf and narrow leaf in dnl1mutant was explained perspective from histocytology The main results are as following:1. The dnll mutant was crossed with Xiushui09(wild type) so as to analyze the dwarf and narrow leaf trait genetically. In the Fis, all the hybrids displayed same as the Xiushui09. In the F2segregation population, the number of individuals was found to be similar to the mutant and the number of individuals was found to be similar to the wild type were fitting the1:3ratios. The result indicated that dnl1mutant trait was controlled by a single nuclear-encoded recessive gene.2. Compared with its wild type Xiushui09, dnl1mutant significant difference in seedling height at two weeks after seeding, dnl1mutant tillering earlier and have more tillers. Plant height of dnll mutant is only55.69%of wildtype, but the number of tillers is2.19fold of wildtype. dnl1mutant significant difference in length of spike and internodes compared with wildtype. Leaf width of wildtype is more than2fold of dnl1mutant and leaf length of wildtype is more than1.6fold of dnl1mutant.3. The DNL1gene was finally mapped on chromosome4by map-based cloning approach. Sequencing and blast analysis indicate that DNL1is an allele to the gene NAL1. A single-base substitution (a for g) in the nucleotide8552bp of NAL1. It result in the asparagine instead of the aspartic acid it’s encoded.4. Paraffin section shows that mesophyll cell of dnl1is smaller than wildtype. Cross section show a thick leaf of dnl1than wildtype, and interval between two vascular bundle is near than wildtype. Longitudinal section demonstrate that culm cells of dnl1mutant are narrow and short compared with Xiushui09. These characteristics explained the reason of formation of dwarf and narrow leaf in dnl1mutant perspective from histocytology. Plant senescence is the comprehensive result produced by internal and external factors during the growing and development. To delay the plant senescence, it is of great importance to study the induction factors and regulatory mechanism of senescence. Since huge economic benefits would be brought by delaying the plant senescence, the mechanism of senescence in crops rice was of great importance. Programmed cell death (PCD) is a token of plant senescence, as well as a vital factor in induction of senescence. As an extensive phenomenon existing in inflorescent plant, male sterility puts a vital role in breeding. The male sterility line was used to increase the efficiency of cross breeding, and then increase the output and quality of rice. The excavation and application of male sterility materials is the core of production system of hybrid rice. So SMS1which caused rice early senescence and male sterility was studied here, and the main results were as follow.1. SMS1was found to be encode a UDPase which catalyzes the transform of glucose-1-phosphate and UTP, UDP-glucose and pyrophosphoric acid by bioinformatics analysis.2. SMS1CDS was inosculated into dual-expression vector with pA7-SMS1-YFP in YFP reporter gene and expressed in protoplast of rice. Fluorescence excitation was detected in membrane, cytoplasm and nucleolus, which indicated that SMS1was ubiquitous expressed in rice cell.3. Vector p1300-SMS1Pro-GUS of GUS reporter gene driven by SMS1Promoter and vector pUN1301-SMS1-OE driven by Ubi Promoter were built successfully. And transgene masculine trains was produced by transform of callus of Nipponbare with Agrobacterium tumefaciens. GUS stain revealed that SMS1was found to be expressed in leaf, leaf sheath, node, internode and glume, which expressed strongly in leaf sheath and node, while weakly in glume and leaf apex. Result of Real Time-PCR indicated that the over expression transgene masculine train was over expressed compared with normal Nipponbare. The most over expression level nearly pointed to three hundred times of normal level in Nipponbare.4. Ultrathin slice observation of different sections of smsl mutant and wild type of leaf was made. It was found that smsl mutant cell appeared programmed cell death phenomena like cavum and nucleolus expansion, while the chloroplast and content in wild type of cell was abundant. Loosen cell wall, hazy outline and partially thin cell wall were seen in smsl mutant, while compact cell wall and vivid outline were seen in wild type of cell. It can be speculated that the loss of SMS1encoded UGPase lead to the impediment of cell wall synthesis, and then inducted the programmed cell death which caused the premature senescence terminally in SMS1mutant rice.