【作者】 王翠玲；

【导师】 陈彦惠；

【作者基本信息】 河南农业大学 ， 作物遗传育种， 2008， 博士

【摘要】 光周期是影响植物生长发育的关键环境因素之一,植物开花的光周期敏感反应一直是人们研究的热点。玉米是短日照植物,光周期敏感性是不同纬度和不同海拔地区间玉米种质资源交流的主要限制因子。因此研究热带玉米的光周期反应的分子机理,弱化玉米的光周期敏感性,不但有利于玉米种质的扩增与创新、提高玉米品种对不同地理纬度和播种季节的适应性,而且还能在玉米开花时间的光周期调控方面进行有益的探索。本试验室以对光周期钝感的温带自交系黄早4和对光周期敏感的热带自交系CML288为亲本配置了温热组合黄早4×CML288,本研究在前人工作基础上,通过单粒传法,构建了包含201个家系的重组自交系群体(F10代)。在此基础上,本研究以F10重组自交系群体为基础群休,通过成对交配设计,构建了一套包含278个杂交组合的永久F2群体。2007年分别对RILs群体及“永久F2”在三亚、河南郑州、河南洛阳、北京顺义和北京昌平等5个地点3个不同的光周期环境下进行了田间鉴定,考察了散粉期积温、株高、叶片数等光周期敏感性相关的性状。通过遗传连锁图谱的构建,分别利用重组自交系群体和“永久F2”群体的表型值,对光周期敏感性及相关性状QTL定位及上位性分析;同时利用中亲优势值对杂种优势位点进行了定位和上位性互作分析,主要结果如下:1、构建了玉米温热组合的重组自交系群体。家系个体基因型组成来源于母本黄早4的纯合染色体片段在28.27%-72.15%之间,平均是46.04%;家系个体基因型组成来源于父本CML288的纯合染色体片段在23.63%-65.40%之间,平均为45.61%。在整个群体中,基于分子标记的基因型分析,双亲染色体同源片段分离符合1∶1的理论分离比例,双亲对子代的遗传贡献基本上是平衡的。群体的基因型组成分布呈正态分布,由此也可以认为,本实验采用的玉米RIL群体是一个随机群体,适合于遗传作图、基因定位等基因组分析和育种应用。2、构建了永久F2群体。个体基因型组成中来源于母本黄早4的纯合染色体片段在10.14-44.55%之间,平均为25.22%;个体基因型组成中来源于父本CML288的纯合染色体片段在7.45-48.79%之间,平均为24.64%;双亲的杂合片段在32.52-66.34%之间,平均为50.14%。结果表明整个群体中基于分子标记的双亲染色体同源片段分离符合1:2:1的理论分离比例,与F2群体的基因型频率相似,因此在遗传组成和基因频率上该永久F2群体与同一来源的F2群体基本相似,可以用永久F2群体代替F2群体进行遗传分析。3、选用玉米基因组的713对SSR引物对亲本进行多态性筛选,以重组近交系为基础材料,构建了一个包含237个SSR标记的重组近交系遗传连锁图,覆盖了玉米的10条染色体,总长度1974.7cM,平均间距8.33cM。4、分别利用重组自交系群体和永久F2群体,三个不同的光周期环境下,共检测到151个玉米光周期敏感性及相关性状的QTL,分布在所有10条染色体上。其中重组自交系群体检测到64个,永久F2群体检测到87个,两个群体共同检测到28个。许多QTL在不同的环境下同时检测到,实际上检测到87个不同的光周期敏感性及其相关性状的QTL,其中重组自交系群体实际检测到32个不同的QTL,永久F2群体实际检测到55个不同的QTL,两个群体共同检测到16个不同的QTL。5、将光周期敏感性主效QTL定位在第10染色体上。不同环境中检测到的QTL不同,散粉期积温QTL qDPS4-2、株高QTLqPH1-2、叶片数QTL qLN4-3在不同群体中三个环境下均能检测到;散粉期积温QTL qDPS10-1、株高QTL qPH10-1和叶片数QTL qLN9、qLN10在重组自交系群体和永久F2群体中均在2个长日照环境中检测到,而在三亚短日照环境中未检测到;散粉期积温QTL qDPS3、株高QTLqPH3、叶片数QTL qLN3-1和qLN4-2在重组自交系群体和永久F2群体中均在短日照环境下检测到,而在2个长日照环境下并未检测到。表明控制光周期敏感性及相关性状的数量性状位点在不同光周期环境中特异表达。控制长日照环境下光周期敏感相关性状的QTL集中在第10染色体的10.04区域,控制短日照环境下光周期敏感相关性状的QTL集中在第3染色体的3.05区域。6、利用双向方差分析法,对重组自交系群体和永久F2群体的光周期敏感性相关性状表现进行上位性分析,结果表明上位性互作在整个基因组中大量存在,大部分互作发生在两个单位点效应不显著的位点之间。永久F2群体在不同环境下,所有考察的性状中,检测到的互作类型中均为AA互作最多,AD/DA互作次之,DD互作最少。7、利用改良的复合区间作图法,在3个环境中共检测到19个株高杂种优势位点(HL),分别位于第1、2、3、4、6、7、9和第10染色体上。有些杂种优势位点在多个环境中同时检测到,或位于紧密相邻的位点,实际检测到的单个杂种优势位点(HL)为13个。这些杂种优势位点多数表现为部分显性,少数表现为超显性效应。8、利用永久F2群体,通过双向方差分析,在全基因组水平上对玉米株高中亲优势值进行两位点互作分析,检测到大量显著上位互作。上位性互作具有一定的环境稳定性,且具有环境特异表达的特点。在三亚短日照环境下,检测到的杂种优势上位性互作中,AA互作最多,AD/DA互作次之,DD互作最少。而在河南和北京长日照环境下,检测到的杂种优势上位性互作中,AD/DA互作最多,AA互作次之,DD互作最少。9、在三种光周期环境下,不论是特殊杂合性还是一般杂合性,与株高表现及杂种优势虽然具有一定的相关性,但相关系数较低,不足以用来预测玉米的杂种优势。进一步分析表明,从单个共显性侧邻标记的检测结果看,各标记杂合子并不总表现出比纯合子更高的性状水平,杂合子表现超亲优势的标记比例仅为31.6%。多数标记的杂合子表型值介于两种纯合子之间,表明杂合性对性状的表现并不总是有利的,显性基因的互补或累加可能对本永久F2群体的杂种优势表现的作用更大。单位点水平上的显性、超显性、以及两位点之间的上位性互作是玉米株高杂种优势形成的重要遗传机理。更多还原

【Abstract】 Photoperiod is a major environment factor affecting plant development, and photoperiod sensitivity of flowering time is an important consideration in plant cultivation and breeding. Maize is short day plant and flowering time is affected by photoperiod, what’more, some tropical varieties do not flower under temperate environmental regimes. Sensitivity to photoperiod limits the potential for successful exchange of germplasm across different latitudes. Therefore, it is vital for maize breeders to understand the genetic basis of photoperiod sensitivity in their efforts to integrate tropical germplasm into temperate zone maize breeding. For resolving the geneticbasis of photoperiod sensitivity in maize, in this research , a population of 207 recombinant inbred lines (RIL) derived from a temperate and tropical inbred line cross were developed, and an immortalized F2 population of 278 F1 cross was constrcted by intercrossing of RILs. The“immortalized F2”and the RIL population were evaluated in five location of three photoperiod environment. The performinance data of photoperiod sensitivity and related traits in RIL population and immortalized F2 popultion were used for QTL mapping and digenic interaction analysis; the values of heterosis were used for dissecting the genetic basis of heterosis per se at single-and two-locus level. The main results obtained in this study were concluded as follow:1. A RIL population derived from a temperate and tropical inbred line cross was constructed. the molecular genotypes deriving from parent Huangzao4 were 28.27%-72.15%, the average homozygous genotypes of Huangzao4 was 46.04%; the molecular genotypes of CML288 were 23.63%-65.40%, and the average genotypes of CML288 was 45.61%; The genotypes of the two parents at the marker loci followed 1: 1 theoretical ratio, so the RIL population was a random one and was fit to be used in conduct genentic linkage map and QTL analysis.2. A set of“immortalized F2”population including 278 single crosses was constructed through three round of intermating of 207 RILs. The molecular genotypes of“immortalized F2”population were deduced based on the RILs population according to the mating design. In the“immortalized F2”population, the molecular genotypes deriving from parent Huangzao4 were 10.14-44.55%%, the average homozygous genotypes of Huangzao4 was 25.22%; the molecular genotypes of CML288 were 7.45-48.79%, and the average genotypes of CML288 was 24.64%; whereas the heterozygous genotypes were 32.52-66.34%%, and the average heterozygous genotypes was 50.14%. The genotypes of Huangzao4, heterozygosity and CML288 at the marker loci followed 1:2:1 theoretical ratio, so the genetic components and gene frequency in“immortalized F2”population were similar as a F2 population.3. A genetic linkage map containing 237 SSR polymorphic markers was constructed using RIL population, spanned a total of 1974.3 cM with an average space between two makers of 8.33 cM.4. A total of 151 QTL were detected in three photoperiod environment for photoperiod sensitivity and related traits using RIL population and immortalized F2 population by composite interval mapping. Out of these QTL, 64 QTL were detected in RIL population; 87 were detected in immortalized population and 28 were detected in both population. Many QTL were detected in different photoperiod environment, as a result, a total of 87 different QTL for photoperiod sensitivity and related traits were detected. Out of these QTL, 32 and 55 QTL were detected in RIL population and immortalized F2 population, respectively, and 16 were detected in both populations.5. Different QTL were detected in different photoperiod environment. qDPS4-2、qPH1-2 and qLN4-3 were detected in three photoperiod environment; QTL for flowering time, plant height and leaf number, under long-day conditions, were found clustered on chromosome 10, while QTL for short day conditions resided on chromosome 3. The QTL in the bin 10.04 region of chromosome 10 were detected associated with photoperiod sensitivity and related traits during long-days. These results indicated that this region might contain an important photoperiod sensitivity element.6. Digenic interactions (epistasis) were detected using all possible loci pairs by two-way analysis (ANOVA) between 237 co-dominant molecular markers, and assessed by 1000 times permutaiton tests. A large number of two-locus combinations involving the entire genome were detected for photoperiod sensitivity and related traits. Most interactions occurred between two loci both showing non-significant effects to traits. It clearly demonstrated that epistasis play an important role in the maize genetics basis of heterosis. In the three interaction types (AA, AD/DA and DD) detected in IF2 population, the AA interactions had highest frequency, followed by AD/DA interactions, and the DD interactions had lowest frequency.7. There were 19 (HL) detected for plant height values of heterosis per se in three photoperiod environment. Some heterotic loci were detected in different photoperiod environment. Most of HL showed part-dominance and some showed over dominance effect.8. A lot of digenic interactions of the heterosis for plant height were identified by using two-way analysis (ANOVA). In short day environment, the AA interactions had highest frequency, followed by AD/DA interactions, and the DD interactions had lowest frequency,while the AD/DA interactions had highest frequency and the DD interactions had lowest frequency in long days.9. Neither genome heterozygosity nor special heterozygosity showed strong relationship with plant height in IF2 population under three photoperiod environments. Comparison of trait Performanee among different genotypes in flanking markers of these QTL showed that heterozygosity did not always show higher Performanee than corresponding homozygosity; only 31.6 % of the markers showed overdominanee,and the phenotype value of most of heterozygosity was between the two kind of homozygosity. These results indicated that the complementation and accumulation of dominance gene may play more important roles in the heterosis of plant height. So the overdominance, partial dominance at the single locus and the interaction effects at two loci were the important contributor to plant height heterosis in the IF2 population.更多还原