【作者】 李红民；

【导师】 任正隆；

【作者基本信息】 四川农业大学 ， 生物化学与分子生物学， 2012， 博士

【摘要】 小麦(Triticum aestivum L.)是世界上重要的粮食作物,是人类植物碳水化合物和蛋白质的重要来源。随着社会经济的发展和生活水平的提高,人们对小麦加工的各种精制面食、保健品和营养食品的需求增大,同时更加关注相关产品的品质,因此品质改良已成为我国小麦育种的主要目标之一。通过分子数量遗传学方法,对小麦品质相关性状的品质分析及QTL定位研究,可以为分子标记辅助育种提供理论基础,并加快品质改良的进度。本研究通过对小麦F9-10高代重组自交系群体(RIL)R97×R146两年的主要品质性状进行分析和QTL定位,及F9-10RIL群体R131×R142的小麦籽粒、旗叶蛋白质含量和旗叶谷氨酰胺合成酶活性发育动态的条件QTL定位研究,主要取得以下结果：(1)由于现有研究群体遗传差异大,构建连锁图谱都不同,与QTL连锁的分子标记也不尽相同,所以各自定位的QTL结果难以相互借鉴利用,仅靠连锁图谱的简单比对难以进行准确和有效的分析。因此,本研究利用两个由中国栽培小麦血统的研究材料所构建的高密度连锁图谱数据和一个由Somers构建的一致性图谱数据,重新构建了一个高密度一致性连锁图谱。该图谱包含了617个微卫星标记(Xwmc、Xgwm和Xbarc三套),覆盖的遗传图谱总长度为1881.1cM,平均遗传距离为3.OcM，通过一致性图谱的构建,可为国内小麦分子辅助育种和QTL结果比较分析提供一个更为合适方便的分析基础。(2)由于粉质指数等面团流变学特性相关参数测定费时费力、并且不易一次性操作成功,因此检测时需要大量小麦面粉。而本研究发现,面筋指数与面团流变学特性的相关指标(面团形成时间、面团稳定时间和粉质指数)均存在显著或极显著的相关性,相关系数分别为0.201(P<0.05)、0.678(p<0.()1)和0.48(p<0.01)。并且也有大量文献报道面筋指数与面团流变学特性指标存在显著相关性。因此,在育种的早代材料中可以将面筋指数作为研究面团流变学特性指标的间接快速测定方法。(3)据文献报道,优质的小麦品种分为质量型优质品种(如优质性状是由蛋白质的质量-优质亚基引起的)和数量型优质品种(如优质性状是由蛋白质含量较高引起)两种。本研究通过分析品质性状间的相关性,发现质量型性状(面筋指数、面团稳定时间和粉质指数等)与数量型性状(湿面筋含量、干面筋含量及蛋白质的含量)呈显著或极显著负相关性。这说明具有较高加工品质(如较高的面筋指数和粉质指数)的小麦往往含有相对较低的面筋含量和蛋白质含量。因此,小麦加工品质与数量型性状极有可能处于一个动态平衡,在不打破这一平衡状态的前提下,小麦加工品质的提高势必会降低小麦数量型性状的含量(如面筋指数与蛋白质含量的关系)。(4)小麦蛋白质含量是小麦的一个重要品质性状。通过对小麦蛋白质含量的QTL分析,在RIL群体R97×R146中检测到一个与分子标记Xwmc419-6B连锁的QTL(Q.GPC-6B),且在两年的QTL分析都被检测到。另有研究显示,在相近的遗传位置也存在多个控制蛋白质含量的QTL。因此,在6B染色体分子标记xwmc419-6B附近的染色体片段上极可能存在控制蛋白质含量的QTL/基因簇。(5)戊聚糖是小麦的一个重要抗营养因子,对小麦的营养品质和加工品质均有重要作用。通过对戊聚糖相关性状进行分析,发现戊聚糖中的水溶性戊聚糖是控制籽粒硬度的重要因素。其原因可能是与造粉体膜相连的戊聚糖主要是水溶性戊聚糖,而造粉体膜上的水溶性戊聚糖通过对淀粉-蛋白质复合体粘性的改变,达到对籽粒硬度控制的作用。(6)通过研究小麦的籽粒硬度指数,发现小麦RIL群体R97×R146籽粒硬度指数的分布图呈双峰分布,并通过t检验,双峰分布的群体符合1：1的分离比,这说明该群体中存在一个主效QTL/基因控制小麦的籽粒硬度。而且,经QTL分析检测到一个控制小麦籽粒硬度的主效QTL(Q.H1-7D),其与分子标记xwmc634-7D连锁,两年都被检测到,并且LOD>10、R2>32%。因此,该QTL极可能是造成群体硬度指数分布图呈双峰分布的孟德尔遗传因子。(7)因QTL表达具有时空特异性,并且动态QTL分析方法可以对不同发育时期性状进行精确有效的QTL定位,所以在条件允许的情况下应尽量采用条件QTL动态分析方法。鉴于蛋白质含量对小麦加工品质的重要影响,本研究首次对小麦籽粒和旗叶蛋白质含量以及旗叶谷氨酰胺合成酶活性进行了动态QTL定位,并在不同时间段定位到四个对表型变异具有较大贡献率的QTL,即Q. GPC-1B.1(LOD=5.2R2=16.6%)、 Q. LPC-2B.1(LOD=4.3R2=28.2)、Q. LPC-1B.2(LOD=8.1R2=32.2%)和Q.GS-1B.1(LOD=3.8R2=29.4%)。T6(4.30|4.25)时间段,在分子标记Xwmc419x-Xwmc44之间同时检测到控制小麦籽粒及叶片蛋白质含量的两个QTL, Q.GPC-1B.3和Q. LPC-2B.3。更多还原

【Abstract】 As one of the most important grain crop, common wheat (Triticum aestivum L.) is the main food of35%of population of the world. People pay more attention to the quality of wheat foods as living standards have improved. So, improvement of wheat’s nutritional quality becomes an important objective in wheat molecular breeding programs. Through the methods of molecular quantitative genetics, we can enhance the power of molecular marker-assisted breeding and the progress of wheat quality improvement. In this research, major quality traits analysis and QTL detection are firstly carried out on the RIL R97×R146; then the protein content in kernel and leaves, Glutamine synthetase activity in leaves of RIL R131×R142are analysed by conditioned QTL mapping methods. The main results are as follows.(1) Because of great genetic variation of wheat populations and diversity of genetic linkage map, it is difficult to draw lessons from the multiple QTL analyzing results. In the research, we have constructed a high-density consensus map with two high density genetic map, which have Chinese cultivated wheat genetic background, and a consensus map data. It contains617SSR markers (Xwmc, Xgwm and Xbarc) and covers1881.1cM. The high-density consensus map will be a new tool for multiple QTL results analysis and moleculer marker-assisted breeding.(2) The detection of dough rheology characteristics is laborious, time-consuming and need much flours. Our research shows that gluten index is significantly positively correlated with dough rheology characteristics (Farinogram Quality Number, dough development and stabilization time) and the correlation coefficients is0.201(P<0.05), 0.678(P<0.01)and0.48(P<0.01), respectively. So gluten index can be a rapid determination method for dough rheology characteristics detection in the early generation materials selection of wheat quality breeding.(3) It has been reported that high quality wheat is divided into quality type and quantity type. In the research, we find that quality traits (gluten index, Farinogram Quality Number) are significantly or high significantly negatively correlated with quantity traits (gluten content, protein content). It means that high quality wheat tends to have low gluten and protein content. Apparently, wheat quality and associated quantity traits are always in a dynamic state of equilibrium.(4) Protein content is an important qulity trait in wheat breeding. We have detected one major QTL (Q.GPC-6B) for protein content in RIL R97XR146. Q.GPC-6B is linked to marker Xwmc419-6B, which can steadily express in multi-environment. Others researches also detect QTLs for protein content in the similar genetic locus. So, there may be one QTL/genes cluster for protein content in the genetic locus which links to xwmc419-6B on chromosome6B.(5) Pentosans are important albeit quantitatively minor constituents of wheat grain. They are significant anti-nutrient factor and have important impact on end-use quality of cereal grain. In this study, we believe that water-soluble pentosan is the major component in pentosans which associate with amyloplast membranes. The association of water-soluble pentosan with amyloplast membranes could modulate the adhesion of starch-protein matrix and therefore has an impact on grain hard index.(6) In the grain hard index (HI) analysis, we find that distribution of the RIL population is bimodal. Using our classification criterion, we classify58RIL lines as high HI and43RIL lines as low HI. The results indicate that there is a single Mendalian genetic factor in this population for grain hard index as the segregation pattern for HI is1:1(χ2=1.66). At the same time, we also find a major QTL Q.HI.scau-7D (LOD>10、R2>32%). This QTL may be the Mendalian genetic factor in this population.(7) Because of temporal spatial expression of QTL, dynamic QTL analysis can accurately detect the QTL in the different development periods of wheat. So, the protein content of kernel and leaves, the Glutamine synthetase activity of leaves are firstly analysed and detected by conditioned QTL mapping method. We have detected four QTL with higher percentage of phenotypic variation. They are Q.GPC-1B.1(LOD=5.2, R2=16.6%), Q.LPC-2B.1(LOD=4.3, R2=28.2), Q.LPC-1B.2(LOD=8.1, R2=32.2%) and Q.GS-1B.1(LOD=3.8, R2=29.4%). We also detecte two QTL (Q.GPC-1B.3and Q.LPC-1B.3) for protein content of kernel and leaves between Xwmc419x and Xwmc44at T6(4.30|4.25).更多还原