【作者】 刘文俊；

【导师】 何予卿；

【作者基本信息】 华中农业大学 ， 生化与分子生物学， 2007， 硕士

【摘要】 随着人们生活水平的提高和市场经济的发展，稻米品质改良越来越受到育种家的关注，特别是在南方杂交稻区，培育优质稻米已成了重要的育种目标。据前人的研究表明，稻米中的脂类不仅是大米重要的营养成分，还与米饭的蒸煮食味品质和储藏品质有关。研究表明：随着品种米质级别的提高脂肪含量增加，脂肪含量越高米饭的蒸煮食味品质越好；脂肪含量越高光泽度越好，延伸性佳。脂肪含量已成为评价大米品质优劣的一项重要指标。因此研究稻米脂肪含量的遗传基础，找到控制稻米脂肪含量的QTL，通过分子标记辅助选择改良稻米品质具有重要意义。本研究以一个含190个株系的籼粳交F₁（珍汕97／武育粳2号）经花药培养的双单倍体群体为基础，分别与两个亲本回交获得了分别包含有149和147个家系的回交群体。以这三个群体为材料，采用索氏抽提的方法对稻米中的粗脂肪含量进行了测定，然后运用QTLMapper1.6分析软件对控制稻米粗脂肪含量的QTL进行定位和遗传效应分析，揭示稻米脂肪含量的遗传机理。主要结果如下：三个群体一共定位到14个QTL，其中在DH群体中定位到6个QTL，分别位于水稻第1、3、5、7、9染色体上，可解释总变异的42.37％。两个回交群体，BC（珍汕97）和BC（武育粳2号）均检测到4个QTL，分别位于水稻第3、5、7、8染色体上和1、3、5、7染色体上。在BC（珍汕97）群体中4个QTL联合效应贡献率为69.4％。在BC（武育粳2号）群体内4个QTL的联合效应为68.42％。在所有这些QTL中，第5染色体上位于RM87-RM334标记之间的位点效应最大，并且在三个群体内都重复检测到。另外有两个位点同时在两个群体中检测到。分别是位于第7染色体上RM346-RM70之间的位点在DH群体和BC（珍汕97）群体中都检测到；位于第3染色体上RM132-RM175之间的位点同时在DH群体和BC（珍汕97）群体中检测到。这几个位点是该群体内控制稻米中粗脂肪含量的稳定遗传的QTL，可以用于MAS改良水稻脂肪含量从而改善稻米品质。同时，在三个群体中还检测到5对上位性互作位点。对这三个群体中各家系的粗脂肪含量的统计分析发现，当DH系与脂肪含量高的亲本珍汕97回交时，回交后代的脂肪含量有升高的趋势；当DH系与脂肪含量低的亲本武育粳2号回交时，回交后代的脂肪含量有降低的趋势。这一结果说明通过回交选育的方法来改良稻米品质选择脂肪含量较低的亲本与待改良品种回交不利于提高脂肪含量。更多还原

【Abstract】 With peoples’ life level and market economics developing, concern of rice qualityimprovement was increasingly received. Especially, in recent years, improvement of ricebetter taste has become major subjects for many breeding programs in Southern China,where more and more hybrid rice was planted. Crude fat acid （CFC） is not only one ofmajor nutritional substance of rice, but also it can influence eating and cooking quality ofrice. As it was showed by someone else, fat content of rice will be increased with theclass of rice quality improvement, and the more of crude fat content, the better of the riceelongation and the quality of rice when rice was cooking. So it is. necessary tocomprehensively clarify its genetic mechanism for rice quality improving program.In this study here, a DH population concluding 190 lines derived from anotherhybrid F₁ between Zhenshan97B（indica） and Wuyujing2（japonica）, and two backcrosspopulations from the DH lines backcrossed to two parents respectively were used to scanQTLs and dissect gene effects for the crude fat content. The aim is to provide theories forimproving rice quality by molecular marker-based selection. The main results were asfollowed:In three populations, fourteen QTLs were resolved, distributing on chromosome 1, 3,5, 6, 7, 8 and 9. Six QTL were detected in DH lines, and these QTL explained 42.37% ofphenotypic variation collectively, and four QTL were detected in two backcrosspopulations BC（Zhenshan97） and BC（Wuyujing2） respectively. Four out of fourteen lociwere detected repeatedly in both populations, DH and backcross populations Such as, thelocus on chromosome 7 between RM346-RM70 was detected in both populations, DHlines and BC（Zhenshan97）. And another locus located on 3rd chromosomes betweenRM132-RM175 was also scanned in two populations, DH lines and BC （Zhenshan97）.Among of these loci, a major QTL qCFC5 was located on chromosome 5 betweenmarkers RM87-RM334, which was detected simultaneously among three populations.Then, 5 digenic epistac QTLs were detected in three populations. By QTLs analysis, weconcluded that main-effect QTLs play a major role in controlling crude fat content ofbrown rice with modifying by several min-effect QTLs and epistatic effects. It can be concluded from the analyses of descriptive statistics for fat content in threepopulations that crude fat content will increase when DH population backcrossing to ahigher value parent, and will decrease when backcrossing to a lower fat content parent.更多还原