【作者】 刘鑫燕；

【导师】 顾铭洪； 徐明良；

【作者基本信息】 扬州大学 ， 作物遗传育种， 2004， 硕士

【摘要】 颗粒结合淀粉合成酶(GBSS)，淀粉分支酶1(SBE1)和淀粉分支酶3(SBE3)是水稻胚乳中淀粉合成所涉及到的三个最主要的酶。这三个酶主要是由Wx，Sbe1和Sbe3基因控制。Wx基因与水稻的直链淀粉合成有关，而Sbe基因主要与水稻的支链淀粉合成有关。Sbe1和Sbe3基因序列可以从基因库中获得。其序列一方面来自于籼稻品种“93-11”，另一方面可从粳稻品种“日本睛”中获得。序列的差异性可通过这两品种的同源序列比较获得。利用基因序列间的差异性，可以发展基因标签标记来区分Sbe1和Sbe3位点上的基因来源。通过四个与Sbe基因有关的新发展的基因标签标记和一个已发表的与Wx基因有关的标记来检测DH群体(南京11×Balilla)，可以得出淀粉各相关基因对水稻直链淀粉含量的影响。Wx基因和Sbe3基因对水稻直链淀粉的含量影响比较大，而Sbe1基因对直链淀粉含量的影响不大，在后代各株系中未达到显著水平。在DH群体中，含籼型Wx~a基因型的株系，其平均直链淀粉的含量比含粳型Wx~b基因型的株系约高9.1％，而含籼型Sbe3~a基因型的株系，其直链淀粉含量的平均值比含粳型Sbe3~b基因型的株系要低1.0％。Wx基因和Sbe3基因之间存在着互作效应。当Wx~a等位基因存在的情况下，含籼型Sbe3~a基因型的株系，其直链淀粉含量的平均值比含粳型Sbe3~b基因型的株系要高0.3％，但是一旦Wx~b等位基因存在，情况则相反，含籼型Sbe3~a基因型的株系，其平均直链淀粉含量的值比含粳型Sbe3~b基因型的株系要低2.3％。总之，Wx基因和Sbe3基因两位点的多态性可以解释DH群体中直链淀粉含量变异的79.1％。此文中同时也讨论了发展基因标签标记对分子标记辅助选择的重要意义，其对基因功能的分析也有一定的作用。更多还原

【Abstract】 The granule-bound starch synthase (GBSS), starch branching enzymes 1 (SBE1) and 3 (SBE3) are three major enzymes involved in starch biosynthesis in rice endosperm. The granule-bound starch synthase encoded by the Wx gene controls the synthesis of amylose .while starch branching enzymes are mainly in charge of the synthese of amylopectin. Available sequences of Sbe 1 and Sbe3 genes encoding corresponding SBE1 and SBE3 have been used to identify homologous regions from genome databases of both the indica rice 93-11 and the japonica rice Nipponbare. Sequence diversities were exploited to develop gene-tagged markers to distinguish an indica allele from a Japonica allele for both Sbel and Sbe3 loci. With these newly developed gene-tagged markers and available Wx gene markers, the roles of these starch-synthesizing genes (Sbel, Sbe3, and Wx) in determining amylose content(AC) in the rice endosperm were evaluated using a double-haploid (DH) population derived from a cross between the indica rice Nanjing 11 and the japonica rice Balilla. Only the Wx and Sbe3 loci had significant effects on the AC variation. On average, indica Wx genotypes showed -9.1% higher AC than japonica Wx genotypes, while indica Sbe3 genotypes showed ~1.0% lower AC than japonica Sbe3 genotypes. A significant interaction was also observed between Wx and Sbe3 loci whereby the amylose content was 0.3% higher in Sbe3 than Sbe3 genotypes in the presence of the Wx allele, but it was lower by 2.3% in the presence of the W allele. Overall, polymorphisms at the Wx and Sbe3 loci together could account for 79.1% of the observed AC variation in the DH population. The use of gene-tagged markers in marker-assisted selection and gene functional analysis was also discussed.更多还原