【作者】 章志宏；

【导师】 朱英国；

【作者基本信息】 武汉大学 ， 遗传学， 2004， 博士

【摘要】 随着水稻直播栽培面积的扩大,对水稻品种种子活力的要求日益提高,水稻种子活力的遗传改良也便成为水稻育种的重要目标之一。DNA分子标记技术的发展和水稻高密度遗传图谱的构建,为剖析包括种子活力在内的数量性状的遗传基础提供了有效手段。本研究利用来源于杂交组合Lemont/特青的一个重组自交系群体,对水稻种子活力的相关性状进行QTL分析。 1、利用纸卷法在3个不同温度条件下进行实验室发芽试验,测定萌发率、根长、芽长和芽苗干重等性状。结果表明,2个亲本之间的差异与温度有关,亲本特青在25℃和20℃的正常温度条件下表现良好的发芽性能,但对15℃低温敏感,表现出显著的基因型与环境温度间的互作。在RIL群体中,4个种子活力性状均呈现出连续变异,并在高值和低值2个方向上表现出超亲分离。QTL定位共检测到34个QTL,其中82%成簇分布在染色体3、5和8的5个染色体区段上,分别将这5个染色体区段命名为QTL qSV-3-1,qSV-3-2,qSV-5,qSV-8-1和qSV-8-2。各QTL对种子活力性状的贡献率均较小,表明种子活力性状受多基因控制:3个QTL(qSV-3-1、qSV-3-2和qSV-8-1)在3个不同温度条件下的作用相对稳定;而另外2个QTL(qSV-5和qSV-8-2)主要在20℃和25℃温度条件下起作用,在15℃低温条件下作用甚微或不起作用,基因型与环境温度间的互作表现为QTL的特异性。当QTL对种子活力的多个性状产生影响时,加性效应的方向总是一致的,QTL qSV-3-1和qSV-8-1的增效基因型来自于亲本Lemont,而QTL qSV-3-2、qSV-5和qSV-8-2的增效基因型来自于亲本特青。 2、建立了纸板播种法,并成功地用于了水稻田间成苗特性的测定。纸板播种法能有效控制田间成茁特性测定试验中的环境误差,广泛适用于各种作物种子田间成苗特性的测定试验。 3、利用纸板播种法在田间湿润和淹水2种条件下,测定出芽率、出苗率、苗高和苗干重等田间成苗特性相关性状,结果表明,特青在这些性状上均显著优于亲本Lemont;在RIL群体种,各性状之间均呈极显著正相关,但相比之下,湿润或淹水处理内性状之间的相关程度(湿润处理内r=0.66～0.80,p<0.001;淹水处理内r=0.56～0.95,p<0.001)明显强于处理之间的性状相关(r=0.14～0.50,p<0.05～0.001)。在湿润处理中,对出苗率、苗高和苗干重3个性状共检测到9个主效应QTL,单个QTL对性状的贡献率为5.7～14.0%,所有QTL的增效等位基更多还原

【Abstract】 Seedling vigor is one of the major determinants for stable stand establishment in rice (Oryza sativa L.), especially in direct seeding cropping system. In the current study, mapping of QTL for seedling vigor related traits was conducted to dissect the genetic basis of seedling vigor in rice using recombinant inbred lines derived from a cross between Lemont (japonica) and Teqing (indica).1、 The recombinant inbred lines were assessed for four seedling vigor traits by paper-roll tests at three temperatures of 25℃, 20℃ and 15℃, respectively. Using a linkage map with 198 marker loci, the main-effect QTL for the traits were mapped by composite interval mapping. A total of 34 QTL for the four seedling vigor traits were identified. Of these QTL, the majority (82%) was clustered within five genomic regions, designated as QTL qSV-3-1, qSV-3-2, qSV-5 qSV-8-1, and qSV-8-2, respectively. All of these five QTL had small individual effects on the traits, explaining 3.1 to 15.8% of the phenotypic variation with a mean of 7.3%. QTL qSV-3-1, qSV-3-2 and qSV-8-1 showed almost consistent effects on the traits across all the three temperatures while QTL qSV-5 and qSV-8-2 produced effects mainly at the normal temperatures of 20℃ and 25℃. Thus significant genotype x environmental temperature interactions appeared to be QTL-specific.2、 The paper plate test was newly develop and was succefully used in evaluating the field seedling establishment characteristics in rice. This newly developed method has proved to be effective in controlling environmental error and useful in testing field seedling establishment characteristics in many plant crops like rice.3、 All the RILs and their parents were evaluated for the field seedling establishment characteristics in both upland and flooding field conditions by paper plate tests.The parent Teqing was superior to the parent Lemont in all the traits investigated. Continuous variation and transgressive segregation in both directions were observed in the RIL population. In the upland treatment, 9 main effect QTL for 3 seedling establishment related traits were detected, each explaining 5.7~14.0%of the trait variation and the positive alleles all contributed by the parent Teqing. In the floodingtreatment, 8 main effect QTL for 4 seedling establishment related traits were mapped, also each with small effect on the trait. On the basis of co-location analysis of all the QTL detected, it was found that two QTL, qSE-1-1 and qSE-3-2, showed additive effects on both coleoptile and seedling emergence only under the flooding field condition, while the other two QTL, qSE-5-1 and qSE-JO, produced additive effects on the multiple seedling establishment related traits under both the upland and flooding field conditions.Comparison of QTL for lab germinability and field establishment characteristics revealed that: a) there were four chromosomal regions, two on chromosome 3 and other two on chromosome 5, which showed additive effects on both lab germinability and field establishment characteristics, b) there were two chromosomal regions on chromosome 8 displaying effects only on lab germinability while the other two, each on chromosomes 1 and 10, produced effects only on field establishment characteristics.4^ Cold tolerance at early seedling stage of rice is one of the major determinants for the stable stand establishment in temperate and high-elevation areas. In the current study, the recombinant inbred lines were evaluated for the cold tolerance at early seedling stage by the paper-roll tests in a two-replication trial with 10 d and 13 d treatments at 10°C, respectively. Composite interval mapping was conducted to locate both main-effect and digenic epistatic QTL for the trait. Three main-effect QTL were identified. The comparison of the QTL identified in these two cold treatments resulted in an intriguing finding that seedling cold tolerance in the 10 d cold treatment was regulated by many loci each with minor effect while that in the 13 d cold treatment was controlled by a major QTL as well as minor ones. Of the three main-effect QTL, QTL qSCT-U, closely linked to microsatellite marker RM202 on chromosome 11, was found to increase its additive effect from 4.07% to 10.11% (seedling survival percentage) as the duration of cold stress was prolonged from 10 d to 13 d. In the 13 d cold treatment, QTL qSCT-11 was detected at a very high LOD score of 19, explaining up to 30% of the phenotypic variation. The identification of QTL for the trait is important for the development of rice cultivars with a broader climatic adaptation.更多还原