【作者】 钟代斌；

【导师】 应存山； 罗利军； 黎志康；

【作者基本信息】 中国农业科学院 ， 作物遗传育种， 2000， 博士

【摘要】 水稻是我国主要粮食作物之一。水稻的许多重要农艺性状大多是数量性状，其中包括株型、产量、米质和抗性等。这些性状一直是水稻遗传改良的重点。抗倒性是株型及产量改良的重要目标性状之一，因而研究水稻抗倒性有关性状的遗传基础具有十分重要的理论和实践意义。抗病育种也是我国水稻改良的重要内容，白叶枯病是我国乃至世界水稻生产的重要病害之一，对白叶枯病主基因抗性（质量抗性）研究较为深入，而对水平抗性（数量抗性）的研究和利用却较少。近年在水稻分子标记技术及基因组研究方面的深入发展为研究这些数量性状提供了新的手段和方法。 本研究以一套由Lemont/特青衍生的重组自交系群体(F₁₄)为材料，构建一个以PCR标记为主的分子连锁图谱；1999年旱季和雨季在菲律宾国际水稻所对该重组自交系进行试验，考查了水稻15个抗倒伏的组分性状及落粒性；对该群体用菲律宾6个白叶枯病菌小种进行了田间接种评价。主要结果如下： 1．构建了一个具有256个遗传标记，分布较好的完整的分子连锁图谱，其中包括115个SSR标记、84个RAPD标记、47个RFLP标记、7个同功酶标记和3个形态标记。该图全长1938.8cM，标记间平均距离为7.6cM。70％的标记位点在RI群体中分离比例为1:1，而30％标记位点偏离孟德尔期望值。偏分离标记主要分布于染色体6、7、8和11的末端。Lemont基因型在群体中占46.1％。该遗传图谱中SSR标记和RFLP标记与康耐尔大学的图谱上的顺序一致。该图谱适合于对该群体进行持续性的遗传研究。 2．研究了与水稻抗倒伏性有关的三组性状共15个，包括茎杆基部节间有关性状4个、株高及组分性状6个和基本营养生长有关性状5个。除株高、伸长节间数和第三节间长外，所有性状在双亲之间均存在显著或极显著差异。几乎所有性状在重组自交系中的分离均表现有双向越亲分离。利用QTLMapper 1.0对各性状进行QTL定位分析，15个抗倒有关性状共检测到65个分布于19个基因组区域的显著的主效QTL及68对显著（P＜0.001）的互作位点。各性状QTL个数由3个到7个不等，单个QTL解释的遗传变异范围在5.0％到34.3％之间，每一性状均有来自某一亲本的增效和减效的QTL存在。在所检测到的68对互作中，只有一对是发生在主效QTL位点之间，另有11对发生在QTL位点与非连锁标记位点之间，其余互作均发生在非连锁标记位点之间。这些QTL和互作标记位点有利于阐明水稻抗倒伏性的遗传机制，也为标记辅助选择改良水稻抗倒伏性提供0I 了理论依据。 3．研究了菲律宾6个白叶枯病菌小种在RI群体中的表现，接种鉴定结果表明：来 自特青的主基因厂b4)抗小种1、小种4和小种5，定位于染色体11上AJ1306一IUi224 区间内；Xa4对小种1、4和5的抗性表现为显性主基因遗传，Lemont感所有6个小种。 当用6个小种接种RI群体时，RI群体对6个小种的反应均表现有超亲分离，特青等位基 因在 XQ4位点可分别降低 4．scm、2．6cm和 4．scm的病斑长度。同时还定位了 12个主效 QTL及 23对显著的互作位点与对 6个白叶枯病菌小种抗性有关。12个 QTL分布于水稻 12条染色体的 9条上，每个 QTL对 2－6个小种有效。对小种 2、5和 6，各检测到 8个 QTL； 对小种 1和 4，各检测到 7个 QTL；对小种 3，只检测到 3个 QTL。QBb］二位于染色体 12 上 RM247－OSR20的区间内，该QTL对所有 6个小种均有效应，其中对小种 5和 6的效 应最大。对小种1、2、5和6，各检测到3对互作；对小种3和4，分别检测到7对和4 对互作。在这些互作中，只有一对是发生在QTL之间的互作（小种3），而大多数互作是 发生在非 QTL之间的互作。互作对小种 3的效应最大。 4．在水稻收获脱粒过程中，落粒性是影响籽粒产量损失的重要因素。本研究定位了 6个控制水稻落粒性的 QTL和 5个控制每穗粒数的 QTL，其中一个控制落粒性的 QTL具 有较大的效应，定位于染色体2（QSh 2），单独贡献率为23二％。6个控制落粒性的QTL累 加贡献率为67．7％，同时检测到4对互作影响落粒性，每对互作贡献率在3．8％·4．8％之间。 5个控制每穗粒数的 QTL累加贡献率为 61．8％，其加性效应范围在门．二－22．4粒之间，其 中QGh4效应最大，单独贡献率为22．3％。还检测到4对互作影响每穗粒数。 以上结果为标记辅助选择改良水稻抗倒伏性、抗白叶枯病及落粒性提供了理论依 据，同时也有利于进一步阐明水稻抗倒伏性的遗传机制，有利于累加抗性基因／QTL提高 水稻对白叶枯病的抗性水平，也有利于进一步弄清水稻落粒性的遗传机制。更多还原

【Abstract】 Rice is one of the most important grain crops in China. Most of the important agronomic traits in crops are quantitative such as plant type, yield component, rice quality, and resistance to diseases and insect etc. Improvement of these quantitative traits is one of the major objectives in crop genetic breeding program. Lodging resistance has been a key target trait for raising yield potential and is associated with many component traits such as height, stem strength and thickness, etc. While phenotypic selection for lodging resistance selection has been effective, its genetic basis remains poorly understood. Bacterial blight (BB) caused by Xanthomonas Oryzae pv. oryzae (Xoo) is one of the most destructive diseases of rice throughout the world. DNA markers and derived molecular linkage maps have provided powerful tools for molecular dissection of monogenic traits and Mendelian components of quantitative traits. A complete and well-distributed molecular linkage map with 256 markers was constructed using a set of recombinant (RI) lines (F14) obtained from an inter-subspecific cross between an Oryza saliva L. ssp. Indica cultivar (Teqing) and ajaponica cultivar (Lemont). It is consisted of 115 simple sequence repeat (SSR) markers, 84 random amplified polymorphic DNA (RAPD), 47 restriction fragment length polymorphism (RFLP) markers, 7 isozymes, and 3 morphological markers. The genetic map spanned 1938.8cM and covered all of 12 rice chromosomes with an average distance of 7.6 cM between adjacent markers. Segregation of 70% of the markers fit the 1:1 Mendelian expectation, whereas the remaining 30% of markers showing segregation distortion largely clustered in the end regions of chromosome 6, 7, 8, and 11. On average, Lemont alleles accounted for 46.1% of the genome of the RI population. Almost all SSR and RFLP markers were mapped to their reported chromosomes and had the linear orders matching perfectly with the previous genetic map. This map have been used for mapping genes and quantitative loci (QTLs) affecting traits segregating in the population. Three groups of component traits, which may potentially contribute to lodging resistance x in rice, included stem thickness related traits, plant height related traits and vegetative growth traits. For all the tested traits, except LUTN, PH, and NEI, there were significant difference between Lemont and Teqing. Transgressive segregation was observed for all the traits examined. QTLMapper version 1.0 was used to detect main-effect and epistatic QTLs associated with the 15 lodging resistance traits in the RI population. A total of 65 significant main-effect QTLs distributing 19 genomic regions of all the 12 rice chromosomes and 68 pairs of significant (NO.001) digenic epistatic loci, were detected for all the tested traits. The number of significant QTLs affecting each trait ranged from 3 to 7. The percentage of genotypic variation explained by each QTL ranged from 5.0% to 34.3%. For those traits for which two or more QTLs were detected, alleles for increased trait values were from both parents. Only one significant interaction occurred between main-effect QTLs (for HD), and 11 interactions occurred between main-effect QTL5 and 慴ackground?loci. All of the other interactions occurred between unlinked 慴ackground?loci. These QTLs and epistasis provided useful information for marker- assisted selection (MAS) for these traits, and for improvement of rice lodging resistance. GenesIQTLs affect更多还原