【作者】 刘静；

【导师】 徐辰武； 杨泽峰；

【作者基本信息】 扬州大学 ， 作物遗传育种， 2015， 硕士

【摘要】 玉米是全球超过9亿人口的主食。玉米淀粉在世界淀粉市场中占据了80%的份额,在食品和工业应用中具有重要的经济价值。淀粉含量和组成是受很多基因控制的复杂的数量性状。研究淀粉合成相关基因和玉米淀粉籽粒品质性状间的关系对优良品种的选育和淀粉品质的遗传改良有重要的指导意义。GBSSI和GBSSIIa基因是颗粒结合型淀粉合成酶（GBSS）基因家族的重要成员,参与玉米籽粒中直链淀粉的合成。本研究首先对91份优良玉米自交系（80份普通玉米自交系和11份糯玉米自交系）中这两个基因的序列进行目的基因重测序,并分析了该二基因在供试玉米自交系群体中的变异情况；在此基础上,基于候选基因的关联分析方法对该基因中的变异位点与玉米籽粒中淀粉糊化特性（包括峰值黏度PV、谷值黏度TV、终值黏度FV、崩解值BD、回复值SB、糊化时间PT、糊化温度PTP）、热力学特性（包括糊化起始温度To、峰值温度Tp、终值温度Tc、热焓值ΔH）和直链淀粉含量AC共12个性状进行了关联分析。分析结果如下：（1）对91份玉米自交系中GBSSI和GBSSIIa基因序列进行多态性分析结果发现：GBSSI基因在91个玉米自交系中共检测到100个SNP（单核苷酸多态性位点）和70个InDel（插入/缺失事件）,平均每43.68bp有一个SNP,每62.4bp发生一个InDel。 GBSS IIa基因在91个玉米自交系中共检测到199个SNP位点和54个InDel,约每34.6bp有一个SNP,每127.4bp发生一个InDel 。（2）方差分析结果表明,12个品质性状在80份普通玉米自交系间和11份糯玉米自交系间均达到极显著水平。相关分析发现,淀粉热力学特性参数与糊化特性参数以及AC间存在一定的相关性：ΔH与TV、FV、SB显著正相关,PTP与Tp、Tc显著相关,AC与AH显著相关。在91份自交系中,无论普通玉米自交系还是糯玉米自交系中AC与糊化特性各性状间均无显著相关关系。（3）基于候选基因关联分析发现,GBSSI基因的两个SNP和两个InDel事件与AC、TV、FV、SB、PTP以及ΔH 6个淀粉品质相关性状存在显著关联,可解释8.14%～22.34%的表型变异。其中位点InDel₃与AC、FV、SB、PTP、ΔH五个品质性状间均存在极显著关联,贡献率分别为19.71%、17.26%、21.97%、8.14%和9.69%；InDel₂与AC极显著关联,贡献率达17.49%。此外,GBSSIIa基因的4个SNP与Tc、TV以及SB 3个淀粉品质相关性状显著关联,可解释表型变异为4.62%-8.09%。其中SNP 9与Tc存在显著关联,为非同义突变,可引起核苷酸序列的改变（L/M）,其表型贡献率为8.09%。更多还原

【Abstract】 Maize is a staple crop for more than 900 million people. Maize starch accounts for 80 percent of the production of starch of the world market, and is of important economic value for food and industry application. The content and composition of starch are complex quantitative traits controlled by a lot of genes, offering multiple potential targets for intervention. Researches on relationships between genes related to starch synthesis and starch quality traits in maize kernels can provide guidance for maize breeding and genetic improvement of starch quality. Granule bound starch synthase gene GBSSI and GBSSIIa are members of Granule bound starch synthase （GBSS） gene family, which are involved in the synthesis of amylose in maize kernel. In this study, we re-sequenced the genomic sequences of these two genes in 91 elite inbred lines （80 normal maize inbred lines and 11 waxy maize inbred lines）, and detected sequence variations as well as their associations with starch pasting properties:Peak viscosity （PV）, Trough viscosity （TV）, Final viscosity （FV）, Breakdown （BD）, Setback （SB）, Peak time （PT）, Pasting temperature （PTP）, and with thermal properties:Onset temperature （To）, Peak temperature （Tp）, Conclusion temperature （Tc）, enthalpy （ΔH） and amylose content（AC）. The major results were listed as follows:（1） Sequence polymorphism analysis showed that 100 SNPs （Single nucleotide polymorphisms） and 70 InDels （insertion and deletions） in GBSSI gene were identified among 91 maize inbred lines. Averagely, a SNP variation occurred every 43.68bp and an Indel occurred every 62.4bp, respectively.199 SNPs and 54 InDels in GBSSIIa gene were found among 91 maize inbred lines. On average, a SNP variation occurred every 34.6bp and an Indel occurred every 127.4bp, respectively.（2） The variance analysis results exhibited that significant differences of the starch quality traits have been found among 80 normal maize inbred lines or 11 waxy maize inbred lines. Correlation analysis revealed some correlations between starch thermal properties and pasting properties, and between starch thermal properties and AC. Specifically, ΔH was significantly positively related to TV, FV and SB; PTP was significantly correlated to Tp and Tc; AC was significantly correlated to AH. Additionally, there was no significant correlation between AC and pasting properties whether in normal maize or waxy maize.（3） Based on the results of candidate gene association analysis, two SNPs and two InDels of gene GBSSI were detected to be significantly associated with six starch quality traits, including AC, TV, FV, SB, PTP and ΔH, which explained 8.14%～22.34% of total phenotypic variations. Among them, InDel₃ was significantly associated with AC, FV, SB, PTP and AH, with contribution of 19.71%,17.26%,21.97%,8.14% and 9.69% to phenotypic variations, respectively; InDel₂ was significantly associated with AC with a contribution of 17.49% to phenotypic variations. Besides, four SNPs of gene GBSSIIa were found to be significantly associated with three traits, namely Tc, TV and SB, explaining 4.62%～8.09% of total phenotypic variation. Among them, one nonsynonymous site SNP₉ resulting in amino acid variation （L/M） was significantly associated with Tc with a contribution of 8.09%.更多还原