基于连锁和关联分析对水稻柱头外露率的研究

发布时间：2018-07-24 13:51

【摘要】：水稻作为发展中国家最主要的粮食作物之一,提供着一半以上世界人口的主食。随着人口的飞速增长,提高水稻产量的意义也变得愈发重要,而杂交水稻的推广是提高水稻产量的一个可行办法。虽然杂交水稻已经大范围商业化,但是不育系的低异交率使得杂交水稻的制种效率普遍偏低和制种成本的增加,从而限制了杂交水稻的推广。柱头外露是影响水稻异交性能的重要因子,柱头外露的颖花的结实率是柱头不外露的颖花的三倍以上,因此改良水稻不育系的柱头外露率可以提高其异交率。近年来学者们定位了许多柱头外露的QTL,但是大部分效应都非常的小,目前也没有利用柱头外露QTL改良不育系柱头外露的相关报道。在本研究中,我们通过连锁分析定位了两个大效应的柱头外露率QTL:q SE2和q SE6,通过关联分析鉴定了三个柱头外露QTL与三个粒形基因共定位,并验证了它们的功能。本研究主要结果如下:1.通过构建高柱头外露率三系不育系超泰A和两系不育系广占63S的BC1F2群体,我们在第二染色体上定位到一个主效的柱头外露QTL基因q SE2,解释群体遗传变异46%。NIL(超泰A)比NIL(广占63S)的柱头外露率高50%,且NIL(广占63S)表现为花粉败育,因此推断q SE2就是光温敏核不育基因tms5。2.利用温敏不育基因tms5紧密连锁的分子标记鉴定Pokhreli和HD9802S的F2群体的育性,我们从中筛选出纯合可育的192个单株用来构建遗传连锁图。在该群体中扫描到三个柱头外露率的QTL,分别是q SE4、q SE6和q SE9。其中q SE6为主效的QTL,在群体中解释柱头外露率遗传变异29%,但是该QTL来源于低值亲本HD9802S。NIL(Pokhreli)比NIL(HD9802S)的柱头外露率低30%。3.对529份多样性栽培稻的花器性状进行全基因组关联分析,对柱头外露相关性状检测到超过50个显著性位点。籼稻和粳稻中检测到的位点大多不同表明籼粳间柱头外露率的遗传差异较大。对于纯系而言,柱头外露率的遗传力较高,属于典型的数量性状,受多个位点效应的影响。应用混合线性回归,5个位点联合解释遗传变异39%,表明柱头外露存在很强的加性效应。4.GWAS检测到的三个关联位点和三个粒形基因共定位,分别为GW2、GS3和GW5。利用这三个基因的三组转基因材料,我们验证了三个位点对柱头外露的效应。通过进一步考察三组转基因材料的柱头性状,我们发现GS3会减小柱托长度,GW5会增加柱头的大小,GW2会降低柱头大小。三个基因对水稻粒形的影响与前人报道相符。因此三个基因通过调控颖壳和柱头的形状来影响柱头外露。5.对529份栽培稻粒形的GWAS表明GS3和GW5是栽培稻粒形变异的主要基因。利用功能性标记检测529份材料的GS3和GW5的基因型,通过回归分析我们发现两个基因都能够解释柱头外露遗传变异20%以上,两个基因联合能够解释30%以上。这些结果表明,GS3和GW5也是控制栽培稻柱头外露率的主要基因。6.为了研究GS3和GW5对于改良柱头外露的可行性,我们将这两个基因划分为四种基因型组合:GW5GS3、GW5gs3、gw5GS3和gw5gs3。通过比较四种基因型组合的柱头外露和产量性状,我们发现GW5gs3这种基因组合具有最高的柱头外露率和产量。而栽培稻中出现频率最高的基因型组合gw5GS3的柱头外露率和产量都最低,因此可以利用优势基因型组合GW5gs3对栽培稻进行遗传改良。7.GW5gs3主要存在于籼稻II和热带粳稻中,而gw5GS3主要存在于籼稻I和温带粳稻中,这种分布的差异表明这GS3和GW5可能受到某种选择。利用这两个基因序列内SNPs分析这两个基因的连锁不平衡,我们发现无论是否考虑群体结构,两个基因间都存在较强的连锁不平衡。通过对两个基因不同基因型和不同基因型组合的核酸多态性分析,我们发现这两个基因可能在育种的过程中受到选择,从而形成不同亚群中GW5gs3和gw5GS3分布的差异,进而导致不同亚群的柱头外露率和产量的差异。
[Abstract]:As one of the most important food crops in developing countries, rice provides more than half of the staple food of the world population. With the rapid growth of the population, the significance of increasing rice yield is becoming more and more important, and the popularization of hybrid rice is a feasible way to improve rice yield. The low cross rate of the breeding lines makes the seed production efficiency of hybrid rice generally low and the cost of seed production increasing, which restricts the popularization of hybrid rice. The exposure of stigma is an important factor affecting the cross cross performance of rice. The seed setting rate of the exposed spikelet is more than three times that of the unexposed spikelet, thus improving the stigma outside the sterile line of rice. The exposure rate can improve the rate of incrossing. In recent years, scholars have located many QTL of stigma exserted, but most of the effects are very small. There is no report on the use of stigma exsertion QTL to improve the exposure of stigma in sterility lines. In this study, we identified two major effects of the exposure rate of stigma QTL:q SE2 and Q SE6 by linkage analysis. The co localization of three stigma exserted QTL and three grain shape genes was identified and their functions were verified by correlation analysis. The main results of this study were as follows: 1. by building high stigma exposure rate three line sterile line super Thai A and two line sterile lines to occupy 63S BC1F2 population, we locate a main effective stigma exposed QTL on second chromophore. Gene Q SE2, which explains the population genetic variation 46%.NIL (A) is 50% higher than that of NIL (63S), and NIL (63S) shows pollen abortion. Therefore, it is concluded that Q SE2 is the fertility of the photoperiod sensitive genic sterility gene tms5.2. using thermo sensitive genic male sterile gene. 192 homozygous plants were screened to construct a genetic linkage map. In this group, the QTL of three stigma exposure rates was scanned, which were Q SE4, Q SE6 and Q SE9., which were the dominant Q SE6, which explained the genetic variation of the exposure rate of stigma 29% in the population, but the QTL was derived from the stigma of the low parent HD9802S.NIL. The total genomic correlation analysis was carried out on the flower characteristics of 529 varieties of cultivated rice with low exposure rate, and more than 50 significant loci were detected for the correlation of the stigma exposure. Most of the detected loci in Indica and japonica showed that the genetic difference between the exposure rate of the stigma between Indica and japonica was larger. For pure lines, the inheritance of the exposure rate of the stigma. High force, which belongs to the typical quantitative trait, is influenced by multiple locus effects. Mixed linear regression and 5 loci combined to explain genetic variation 39%, it indicates that the stigma exsertion has a strong additive effect.4.GWAS detected by three associated loci and three granular genes, which are GW2, GS3 and GW5. using three groups of these three genes, respectively. We verified the effect of three loci on stigma exposure. By further examining the stigma traits of three groups of genetically modified materials, we found that GS3 would reduce the length of the column, GW5 would increase the size of the stigma, and GW2 would reduce the size of the stigma. The effect of three genes on the grain shape of rice was consistent with the previous reports. Therefore three genes passed through the previous reports. The shape of the spikelet and the stigma was regulated to influence the GWAS of the grain shape of 529 cultivated rice with the stigma exsertion.5. indicating that GS3 and GW5 were the main genes of grain variation in the cultivated rice. Using functional markers to detect the genotype of GS3 and GW5 of 529 materials, through regression analysis, we found that two genes could explain more than 20% of the genetic variation of the stigma exposure, two The combination of genes can explain more than 30%. These results suggest that GS3 and GW5 are also the main gene.6. for controlling the exposure rate of stigma in cultivated rice. In order to study the feasibility of GS3 and GW5 for improved stigma exposure, we divide the two genes into four genotypes: GW5GS3, GW5gs3, gw5GS3 and gw5gs3. by comparing four genotypes. We found that the gene combination of GW5gs3 has the highest exposure rate and yield of stigma, and the highest exposure rate and yield of the genotype combination gw5GS3 in the cultivated rice are the lowest. Therefore, the genetic improvement of the cultivated rice with the dominant genotype combination of GW5gs3 is mainly in the presence of.7.GW5gs3 in the cultivated rice. In indica rice II and tropical japonica rice, gw5GS3 mainly exists in Indica I and temperate japonica rice. The difference of this distribution indicates that this GS3 and GW5 may be selected. Using these two gene sequences, SNPs analysis of the linkage disequilibrium of the two genes, we find that there is a strong linkage between the two genes whether or not the group structure is considered. Disequilibrium. Through the analysis of nucleic acid polymorphism of two genotypes and different genotypes, we found that these two genes may be selected in the process of breeding, thus forming differences in the distribution of GW5gs3 and gw5GS3 in different subgroups, leading to the difference in the exposure and yield of the stigma in different subgroups.
【学位授予单位】：华中农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S511

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