【作者】 于彦春；

【导师】 黄大年；

【作者基本信息】 浙江大学 ， 遗传学， 2004， 博士

【摘要】 植物细胞壁是由纤维素等物质构成的网状结构，对细胞、组织和植物体起着重要支持作用。植物机械强度反映了细胞壁的物理特性，也为作物适应于不同的栽培环境提供了条件。水稻株高是决定产量的重要因素，为了理解水稻植株机械强度的控制机制和植物细胞壁生物合成的分子机理以及与植株高度间的关系，我们从转基因的粳稻恢复系C418的T1代中分离了一个水稻脆秆突变体。该突变体还表现出植株显著变矮的多效表型，因此将其命名为dwb1（dwarf and brittle 1）。遗传分析表明该突变体的表型受隐性单基因控制。等位性实验证明该突变体与已报道的水稻脆秆突变体bc1—bc3（brittle culm1—3）均不等位，表明其为一个新的脆杆突变体。细胞壁形态学观察和生化分析的结果显示，DWB1基因的突变引起了机械组织细胞壁纤维素含量减少。这些结果暗示dwb1脆嫩性状是细胞壁缺陷的结果。突变体dwb1的矮杆表型被划分为四种矮杆中的一类一dn型，有关这种类型突变体的精细定位的报道并不多见。激素处理的结果显示，dwb1的矮杆性状表现为GA不敏感型。为了研究DWB1基因的功能，我们从大约8，000株F₂群体中挑选出2056个突变个体用作定位群体，用图位克隆的方法精细定位了DWB1基因。首先将DWB1基因定位在水稻第9染色体的着丝粒附近区域。通过构建覆盖DWB1位点的BAC克隆重叠群，最后将DWB1位点定位在143kb的基因组DNA区域。DWB1基因的分子定位为以后的基因克隆及功能分析打下了良好的基础。更多还原

【Abstract】 The plant cell wall is a strong fibrillar network that provides mechanical support to the cells, the tissues and the entire plant body. The mechanical strength of the plant body, which reflects the physical properties of cell walls, is an important trait for the adaptation of crops to different cultivation environments. The height of plant is important to improve productivity of rice. To investigate the complicated mechanisms of plant cell wall biosynthesis and mechanical strength of the plant in determine of plant height, we isolated the rice dwarf and brittle cu1m1 (dwb1) mutant, a pleiotropic phenotype controlling by a recessive mutant, from a japonica cultivar C418 produced by transgene approach. Allelism tests showed that the dwbl is not allelic to all of previously reported brittle culm mutants, from bc1 to bc3, indicating that it is a new gene determining culm strength and height. In dwbl, the content of cellulose is slight low than wild type, it showed that the phenotype of brittle culm is due to reducing of cellulose content. The dwbl mutant is classified as a dn-type, one of four kind of dwarf, which is the first report about fine-mapping of this kind of dwarf type. Physiological analysis showed that dwbl is insensitive to exogenous GA, indicating that it is controlled by GA signal. However, previous reports about the mutants presenting dwarf and brittle culm phenotype in rice are correlative with ethylene signal. Then, the relationship of GA signal with cellulose synthesis needs to be clear further. To determine the molecular basis of these defects, we tried to isolate the DWB1 geneby a map-based cloning approach. The fine mapping using 2,056 segregants enabled us to construct a BAG contig that encompasses the DWB1 locus, and finally defined it in a 143kb genomic region, which provided an important basis to finally clone it. The mechanism of brittle culm and dwarf phenotype would be elucidated by cloning of DWB1更多还原