【作者】 王涛；

【导师】 李海涛；

【作者基本信息】 沈阳农业大学 ， 蔬菜学， 2016， 博士

【摘要】 番茄是世界上重要的蔬菜作物,番茄品质相关性状一直是番茄育种中的热点,弱光是影响番茄生产的重要限制因素,番茄耐弱光育种是提高番茄品种耐弱光性、减少光照不足造成减产的有效途径,而开发与品质和耐弱光性相关的分子标记,将极大的促进番茄品种改良和种质创新。本文从348份番茄材料中筛选出191份番茄自交系作为关联作图群体。利用3种分子标记(SNP、InDel和SSR)对其进行遗传多样性、群体结构和连锁不平衡(LD)分析。最后对番茄品质和耐弱光相关性状进行基于全基因组扫描的关联分析,检测与目标性状相关联的分子标记。主要研究结果如下：1.利用52个SNP标记对348份番茄自交系进行遗传多样性分析,其中45个SNP标记具有多态性,在整个群体中,所有多态性标记的平均期望杂合度和PIC分别为0.395和0.309。比较不同亚群间的遗传多样性发现,樱桃番茄拥有最高的遗传多样性,美洲番茄次之。群体结构和NJ聚类分析发现,348份番茄自交系可以聚类为3大类群,樱桃番茄、欧洲番茄和中国番茄,中国番茄又可进一步划分为粉果番茄、迟熟番茄和红果番茄。根据348份番茄个体间遗传距离,从中筛选出了191份番茄自交系作为关联作图群体。最后利用SNP标记构建核心种质发现,仅需2%的个体便可以覆盖所有的SNP变异。2.利用273个分子标记对191份番茄自交系进行遗传多样性分析,共有238个标记具有多态性,包括103个SNP、113个InDel和22个SSR。三种分子标记的等位基因频率分布差异较大,InDel和SSR标记拥有较多的低频等位基因。遗传多样性和群体结构分析显示,SNP标记可以检测到更多的遗传变异和群体结构,这说明在分析亲缘关系较近的栽培番茄时,SNP标记具有较高的效率。基于238个分子标记的群体结构分析显示,191个番茄自交系可分为4个或者6个亚群体。LD分析显示,InDel和所有分子标记标记在染色体上的平均LD衰减距离为3～5cM,而SNP标记在染色体上的平均LD衰减距离为10-15cM。3.分别在两个年份对191份番茄自交系的农艺性状进行调查,6个品质相关性状(单果重、果实横径、果实形状、心室数、糖度和果实硬度)在群体内具有丰富的多样性,个体间差异显著,不同的年份间,只有糖度差异显著。利用混合线性模型对6个性状进行关联分析,累计检测到115个显著相关联的标记,其中与单果重性状为10个,果实横径相关的标记为16个,果实形状为38个,心室数为11个,糖度为17个,果实硬度为23个。表型变异解释率在0.8%～14.8%之间,其中表型变异解释率最高的标记为SSR45,与番茄果实硬度相关联。4.本研究在正常光照和遮光两种处理下对191份番茄自交系进行了耐弱光评价,评价指标包括株高、茎粗、叶绿素含量、单果重、坐果率及利用这5个指标计算的相对耐弱光指数。5个指标在两种处理下均差异显著,单果重、茎粗、叶绿素含量和坐果率较对照分别平均下降了33.02%、24.10%、26.50%和39.02%,株高平均增加了28.87%。对5个相对耐弱光指数进行相关性分析发现,5个指数间的相关性均较低,说明这5个性状的遗传规律不同。然后利用238个多态性标记对5个性状进行关联分析,累计检测到73个相关联的分子标记,与单果重相关的标记有14个,与株高相关的分子标记有20个,与茎粗相关的标记有13个,与坐果率相关的有18个,与叶绿素相关的标记最少,为8个。这些相关联分子标记的表型变异解释率在0.3%～4.5%之间。最后对5个耐弱光指数进行关联分析发现,累计检测到48个相关联的标记,与单果重耐弱光指数相关的标记有8个,与株高耐弱光指数相关的有10个,与茎粗耐弱光指数相关的有15个,坐果率耐弱光指数有5个,叶绿素耐弱光指数有10个。表型变异解释率在2.1%～8.7%之间。更多还原

【Abstract】 Tomato(Solanum lycopersicum L.) is one of the most economically important vegetable crops in the world. The quality-related traits are always hotspots of tomato breeding. Weak light is a major limiting factor for tomato production, and plant breeding is the most effective way to improve weak light tolerance and reduce the yield loss. The discovery of molecular markers associated with tomato quality and weak light tolerance will greatly promote variety improvement and germplasm innovation in tomato.In the present study, association mapping population including 191 tomato inbred lines was selected from 348 tomato lines. Genetic diversity, population structure, and linkage disequilibrium (LD) were analyzed based on three types of molecular marker (SNPs, InDels, and SSRs). Finally, association analysis between genotypes and tomato quality and weak light tolerance related traits was performed, and the molecular markers associated with the target traits were detected. The main results were as follows:1. In this study,348 inbred tomato lines were genotyped through 52 single-nucleotide polymorphisms (SNPs), among which 45 were informative for subsequent analysis. Genetic diversity analysis found that average expected heterozygosity and PIC were 0.395 and 0.309, respectively. Among the six subpopulations, Cherry tomato had the highest genetic variation, Chinese tomato came second. Population structure and clustering analysis revealed that 348 tomato lines could be divided into three main groups, corresponding to cherry, European tomato, and Chinese tomato. Chinese tomato could be further separated into three subgroups represented pink, non-ripening, and red tomato. Subsequently,191 lines were selected based on the genetic distance from 348 tomato lines. Finally, a core collection was constructed, and the data showed that only a small number of accessions (2%) were needed to retain all SNP alleles as well as the whole allelic diversity.2. In this study,191 tomato inbred lines were genotyped using 273 molecular markers, 238 markers (103SNPs,113InDels, and 22SSRs) showed polymorphism. Three types of molecular markers were different in distribution of allele frequency, InDels and SSRs had more low frequency alleles. Genetic diversity and population structure analysis showed that SNPs could detected more genetic variation and subpopulations within cultivated tomatoes, this indicated SNPs are more efficient in distinguishing closely related tomato lines. Population stucture analysis based on 238 markers subdivided 191 tomato lines into four or six subpopulation. LD analysis indicated that LD decays over 3-5cM when InDel and all markers was used, while it happened within 10～15 cM when SNP was used.3. In this study, fruit quality-related traits of 191 tomato lines were assessed in two years, the selected traits included fruit weight, fruit diameter, fruit shape, locule number, sugar content, and fruit firmness. Six fruit quality-related traits were significant difference among individuals, and all traits were not significant difference among different years except sugar content. Association mapping for the six traits with mixed linear model,115 significant associated markers were detected. There were 10 for fruit weight,16 markers for fruit diameter,38 for fruit shape,11 for locule number,17 for sugar content, and 23 for fruit firmness. The explanation rate of phenotypic variation ranged from 0.8% to 14.8%, SSR45 explained the highest phenotypic variation for fruit firmness.4. A total of 191 tomato lines were evaluated for weak light tolerance under both well light and weak light environments. The selected criteria included plant height, stem diameter, chlorophyll content, fruit weight, rate of fruit set, and five relative weak light tolerance indexes. Five traits were significant different among two light treats, fruit weight, stem diameter, chlorophyll content, and the rate of fruit set fell by an average of 33.02%、24.10%、 26.50%, and 39.02%, on the contrary, plant height, on average, increased by 28.87%. The correlations of five relatively weak light tolerance indexes were poor, which suggested that the five indexes were controlled by different genetic composition. The results of mapping showed that 73 significant associations were detected. There were 20 associations for plant height, concluding 14 for fruit weight,13 for stem diameter,18 for rate of fruit set, and 8 for chlorophyll content. Finally, five weak light tolerance index for correlation analysis suggested that 48 significant associations were detected. There were 8 associations for weak light tolerance index of fruit weight,10 for weak light tolerance index of plant height,15 for weak light tolerance index of stem diameter,5 for weak light tolerance index of rate of fruit set, and 10 for weak light tolerance index of chlorophyll content, phenotypic variation rates were between 2.1% and 8.7%.更多还原