摘要水稻是我国重要的粮食作物，但是穗发芽的存在严重影响稻米品质和下一季播种的种子质量[1]。近几年利用籼粳杂交培育的水稻新品种均表现了较强的穗发芽特性，生产上的穗发芽现象呈上升趋势。同时杂交稻制种过程中赤霉素使用量的增加，也使穗发芽危害日益增加。穗发芽的产生除了与水稻生长环境条件有关外，还与内在基因存在直接关系。因此有关于延迟水稻发芽突变体的研究具有重要的理论和实际意义。通过EMS诱变籼稻品种“蜀恢（SH）”，得到一个在整个生长期表现为株高矮小、叶片细长，在抽穗期岁发芽率极少的突变体，称其为水稻延迟发芽突变体deg1。该突变体与野生型相比，种子发芽速度慢，整体表型矮小、叶片细长，在相同环境下，抽穗期种子穗发芽率明显减少。以deg1突变体为母本，粳稻品种Nipponbare为父本建构F2定位群体，确定突变体由隐性单基因控制，通过图位克隆方法我们将DEG1基因定位于水稻12号染色体长臂SSR分子标记P2和P4之间，通过对突变基因和野生型该区域的碱基序列的对比，发现水稻基因DEG1编码区的第2410位的碱基由C突变为T，由此编码的第646位氨基酸从精氨酸变为色氨酸。通过对内源性激素ABA和GA含量的测定，SH的GA3含量高于deg11。98%，而ABA的含量低于deg116。3%，说明了高ABA和（或）低GA积累水平可能是导致deg1突变体种子休眠的直接原因。74994

Abstract Rice is one of the most important food crop in China, but the presence of pre-harvest sprouting seriously affect the grain quality and yield。 In recent years, the variety of indica-japonica hybrids showed a strong pre-harvest sprouting (PHS) characteristic。 In addition, the application of gibberellin also contributes a lot to PHS。 Several studies had been explored to understand the mechanism of PHR, so far, both environmental and genetic factors had been considered as major determinant。 By EMS mutagenesis of indica variety "Shuhui (SH)", a mutant presented multiple phenotypies was isolated。The mutant compared to wild type, seed germination was slow, dwarf and slender leaves, moreover, the pre-harvest sprouting was significantly higher in deg1。 To clone the responsible DEG1 gene, a F2 population was produced with deg1 and japonica variety Nipponbare and the DEG1 gene was determined as a recessive gene。 The dwarf and highly PHS plants from F2 population were further used to localize DEG1 gene and the gene was finally localized on the long arm of chromosome 12 between SSR markers P2 and P4。 There were12 putative ORFs were annotated in this distance and one of ORF was found an C mutated to T at the 2410 bases after the start codon, which led to the 646 amino acids from thehistidine change into tryptophan。 By measuring endogenous hormone ABA and GA content, we found the GA3 content in wild type is 11。98% higher than deg1, and the content of ABA below 16。3% in deg1 than wild type, suggesting the highly GA and（or） low level of ABA accumulation in deg1 may contribute to the increase of the seed dormancy。

毕业论文关键词：水稻；穗发芽；休眠；SSR标记；萌发；内源性激素

Key words：Rice；Pre-harvest sprouting；Dormancy；SSR marker；Germination；Endogenous Hormones

目  录

摘    要 1

引言 3

1 材料与方法 4

1。1 水稻材料 4

1。2 实验方法 4

   1。2。1图位克隆 4

   1。2。2水稻叶片DNA的提取 5

   1。2。3目的基因PCR扩增