【作者】 吴青松；

【导师】 万建民；

【作者基本信息】 南京农业大学 ， 作物遗传育种， 2006， 博士

【摘要】 高等植物种间硅(Silicon)含量存在巨大差异，从占地上部分干重的0.1％到10％以上。根据植物硅含量的高低以及Si和Ca的比值，可将植物分为高硅积累型、中等硅积累型和拒硅型三种硅积累类型。高等植物种间硅含量的差异主要来源于根系硅吸收能力的差异，与硅积累类型相应存在三种根系对硅的吸收形式：主动硅吸收、被动硅吸收和拒硅型。植物根系以硅酸的形式吸收硅，硅酸进入木质部后，随蒸腾流被输送到地上部分，以硅胶形式沉积在叶片、茎杆等器官的表皮组织和维管束厚壁组织。提高植物体内的硅含量可以改善植株的受光姿势、增强植物抗倒伏能力、提高植物对多种生物胁迫和非生物胁迫的抗(耐)性、增加产量和提高品质。硅对植物的有益作用随植物硅含量增高而表现明显。提高植物的硅含量除了增施硅肥外，提高根系吸收硅的能力也是一条值得探索的途径。水稻是高硅积累型植物，其根系能主动吸收硅。水稻地上部硅(Si)含量可高达干物质重的10％以上。稻株缺硅，其生长发育会受到影响，后期会因不育而导致减产。我国北方有近40％的稻田缺硅，南方则达50％。培育能从低有效硅土壤中高效吸收硅的水稻品种，增加水稻硅含量，既可改善水稻的受光姿势、增强抗倒伏能力、提高水稻对水分胁迫、盐胁迫、高温胁迫、铝毒、重金属毒害胁迫等多种非生物胁迫和稻瘟病、胡麻斑病、纹枯病、螟虫等生物胁迫的抗性，同时又可减少农药、硅肥等施用量，对水稻的可持续生产具有重要的意义。水稻硅吸收遗传机制的分析有利于阐明水稻硅吸收的分子机理，也有助于选育高效硅吸收水稻品种。本研究利用粳稻品种Nipponbare、Asominori、Kinmaze和籼稻品种Kasalath、IR24、DV85研究水稻品种间根系硅吸收能力的差异；利用Kinmaze／DV85重组自交系(recombinant inbred lines，RIL)作图群体和Asominori／IR24 RIL作图群体对水稻籼粳间的硅吸收能力进行了遗传分析，并对影响水稻单位根干重硅吸收能力(根硅吸收能力)、单株硅吸收能力和水稻根干重的数量基因座(quantitative trait locus QTL)进行了定位。结果如下：1、水稻品种间根系对硅的吸收能力有显著的差异(P＜0.01)，水稻地上部分的硅含量受根硅吸收能力和根冠比的影响。根硅吸收能力低的品种可因较高的根冠比(或相对较低的地上部生长量)而获得较高的地上部硅含量，因而稻株硅含量的高低并不能反应根系硅吸收能力的强弱，地上部硅含量不宜作为根硅吸收能力检测的指标。粳稻品种Kinmaze和籼稻品种DV85的硅酸吸收能力学试验表明Kinmaze和DV85对硅酸具有相近的亲合常数，但它们对硅酸的最大吸收速率存在显著差异。粳稻品种Asominori和籼稻品种IR24的硅酸吸收动力学试验也具有相同的结果，Asominori与IR24对硅酸的亲合常数相近，但最大硅吸收速率存在差异，暗示品种间的硅转运蛋白密度的差异。2、81个家系组成的Kinmaze／DV85 RIL作图群体和由71家系组成的Asominori／IR24 RIL作图群体均表现在单位根干重硅吸收、单株硅吸收和根干重三个性状上的分离，说明这三个性状是数量性状，受多基因控制。两套RIL群体的单位根干重硅吸收、单株硅吸收和根干重三个性状的相关分析表明单株硅吸收与根干重的相关性大于单株硅吸收与单位根干重硅吸收间的相关性，表明水稻单株硅吸收受根量的影响大于受根硅吸收能力的影响；在根干重和单位根干重硅吸收间则存在着负相关。3、利用Win QTL Cartographer 2.5分析软件，通过复合区间作图分析，以Kinmaze／DV85 RIL和Asominori／IR24 RIL作图群体为材料，对影响水稻根系硅吸收能力、单株硅吸收能力和根干重的QTL进行了检测。利用Kinmaze／DV85 RIL群体定位了3个单株硅吸收相关的QTL，分别位于第7、8和10染色体上，解释表型变异的13.2％、11.0％和11.5％；定位了4个与根硅吸收能力(单位根干重硅吸收)相关的QTL，分别位于第1、3、9和11染色体，相应贡献率为11.7％、7.2％、15.1％和12.2％；定位了3个影响根干重的QTL，分别位于第2、3、7染色体上，相应贡献率为17.2％、13.5％和8.1％。利用Asominori／IR24 RIL群体定位了3个单株硅吸收相关的QTL，分别位于第7、8染色体上，相应的贡献率为8.2％、16.1％和10.7％；定位了3个与根硅吸收能力相关的QTL，分别位于第3、7、9染色体上，相应的贡献率为13.5％、12.1％和11.4％；定位了6个影响根干重的QTL，分别位于第1、2、4、7、8染色体上，能解释表型变异的8.9％、7.4％、11.4％、8.5％、18.9％和12.8％。在两套RIL群体都检测到的QTL有：位于第3染色体上的影响根硅吸收的QTL，qSILr-3；位于第7、8染色体上与单株硅吸收相关QTL，qSILp-7和qSILp-8；位于第2、7染色体上影响根干重的QTL，qRDW-2和qRDW-7。4、根据Kinmaze／DV85 RIL和Asominori／IR24 RIL作图群体的单位根干重硅吸收相关QTL的定位结果，从以Asominori为遗传背景置换IR24的染色体片段置换系(chromosome segment substitution lines，CSSLs)AIS中选择包含根硅吸收QTL区间的染色体片段置换株系，分析目标QTL相应的IR24染色体片段在Asominori遗传背景中的效应，结果表明两套RIL定位的根硅吸收相关QTL基本能检测出，表明RIL定位结果的可靠性。本研究结果为进一步对根硅吸收QTL的精细定位及单基因分离奠定了基础。更多还原

【Abstract】 The silicon （Si） concentration of plant shoots varies greatly between plant species;ranging from about 0.1% to more than 10% （w/w） Si on a dry weight basis. Base on the Siconcentration of the plant tops and the Si to Ca ratio, plants are classified in to Siaccumulator, intermediate type, and Si excluder species. The variation in Si concentration islargely due to different capacities for Si uptake by plant roots. Three uptake modes havebeen suggested: active, passive, and rejective uptake, corresponding for the three Siaccumulator types respectively.Si was absorbed by roots in the form of silicic acid. After uptake, silicic acid in thexylem was immediately transported to the shoot together with the transpiration stream.Most of the Si deposited on the surface of leaf, stem, and the sclerenchyma of vascularbundles, in the form of silica gel. Si in plant can stimulate canopy photosynthesis byimproving leaf erectness, decrease susceptibility to disease and insect damage, preventlodging, and alleviate various abiotic and biotic stresses. But, usually the more Siaccumulates in the shoots, the larger is the effect that gained. The utilization of siliconfertilizer was one way to increase Si concentration in shoot of plant, however, improve theability of Si uptake by root is another way that scientists are dedicating to.Rice （Oryza sativa） is a typical plant that shows active uptake of Si, and canaccumulates Si to levels up to 10.0 % of shoot dry weight. Deficiency in Si, the growth ofrice is negatively affected, and the productivity decreases greatly due to reduced fertility. 40% of the paddy soil areas in the southern part of China, are Si deficient; and about 50% ofpaddy soil in the northern part of China are Si-deficient or potentially Si-deficient soils.However, the most strategy is to breed rice varieties with high ability of Si uptake that canget adequate Si from the Si-deficient soil. Thus, rice can get the beneficial from more Si inplant. Improves light interception characteristics by keeping the leaf blade erect, increasesresistance to diseases and pests and lodging, remediate nutrient imbalances, and other beneficial effects, and decrease the usage of pesticide and Si fertilizer, and this will beuseful for the rice sustaining productivity in China. Genetic dissection of silicon uptakeability in rice will be provide a better understanding of the mechanism of rice si uptakeability and a basis for higher Si uptake ability breeding in rice.In this study, three japonica rice varieties-Nipponbare, Asominori, Kinmaze -and threeindica rice varieties-Kasalath, IR24, DV85-was used to analysis the difference in Si uptakeamong rice genotypes, and two mapping population of recombinant inbreed lines （RIL）-Kinmaze （japonica） /DV85 （indica） RIL and Asominori （japonica） / IR24 （indica）RIL-were used to detect quantitative trait loci （QTL） for Si uptake by root and root dryweight. The results were followings:1. Significant difference in Si uptake ability was observed among rice varieties. The Siconcentration in shoot was affected by root Si uptake ability and the root to shoot ratio.Varieties with lower root Si uptake ability can get higher Si concentration in shoot throughhigher root to shoot ratio. Thus, Si concentration in shoot cannot reflect the ability of theroot Si uptake and it did not appropriate to be an index to detect the root Si uptake ability.Kinetics study indicated that the Si transporters in Kinmaze （japonica） and DV85 （indica）had the same affinity for silicic acid, but with different V_max. The same result was observedin the kinetic study of Asominori （J） and IR24 （I）, they had same affinity for silicic acid, butwith different V_max, indicating that difference density of Si transporter in root of rice.2. Two mapping population of recombinant inbreed lines （RIL）-Kinmaze （japonica） /DV85 （indica） RIL and Asominori （japonica） / IR24 （indica） RIL-was used to detect theSi uptake ability in rice. The two RILs followed a continuous one-peak distribution andshow transgressive segregation in both directions for Si uptake by individual plants （SP）, Siuptake per unit root dry weight （SR） and root dry weight （RDW）. Therefore, these threetraits are polygenic inheritance. Low correlation was observed between the SP and SR, buthighly significant correlation between the SP and RDW in the both RILs populationssuggesting that SP was much more affected by RDW than by SR. Root biomass play animportant role in Si uptake per plant, and negative correlations between the SR and RDWwere observed in the two RIL populations.3. Composite interval mapping （CIM） was conducted by using Win QTL Cart 2.5 software to detected QTLs controlling the Si uptake and the root dry weight in the Kinmaze /DV85 RIL and Asominori / IR24 RIL populations.In the Kinmaze / DV85 RIL, three QTLs on chromosome 7, 8 and 10 were identified for SP with the phenotypic variation （PVE） of 13.2%, 11.0%, and 11.5%, respectively.Four QTLs on chromosomel, 3, 9, and 11 were identified for SR with PVEs of 11.7%, 7.2%, and 15.1%, respectively. And 3 QTLs for RDW were detected on chromosome 2, 3, 7with PVEs of 17.2%, 13.5%, and 8.1%, respectively.In the Asominori / IR24 RIL, three QTLs on chromosome 7, 8 were identified for SPwith PVE of 8.2%, 16.1%, and 10.7%, respectively. Three QTLs on chromosome 3, 7,and 9 were identified for SR with PVEs of 13.5 %, 12.1%, and 11.36 %, respectively. And6 QTLs for RDW were detected on chromosome 1, 2, 4, 7, 8 with PVEs of 8.9%, 7.4%,11.4%, 8.5%, 18.9%, and 12.8%, respectively.The QTL qSILr-3 for SR on the chromosome 3 was detected in both RIL. QTLs for SP,qSILp-7 and qslLp-8 were identified in both RILs, which on chromosome 7 and 8,respectively. And QTLs for RDW on chromosome 2 and 7 were detected in the both twoRILs.4. The AIS lines carried the QTL region for SR, which identified in the two RILsmapping populations, in the chromosome segment substitution lines （CSSLs） of IR24chromosome segments in the Asominori genetic background were selected to detect the Siuptake ability by root. The results showed that all the QTLs for SR detected in the Kinmaze/ DV85 RILs and Asominori / IR24 RILs had a corresponding effect. These showed therealty of these QTLs. Thus, the results from this study will provide a better understandingof the mechanism of rice Si uptake ability and the basis for fine-mapping the genesinvolved, and will be useful for the high Si uptake ability in rice breeding program.更多还原