【作者】 岳兵；

【导师】 张启发； 邢永忠；

【作者基本信息】 华中农业大学 ， 生物化学与分子生物学， 2005， 博士

【摘要】 干旱尤其是生殖生长阶段干旱胁迫是制约水稻生产的一大障碍，而各种抗旱机制相互重叠影响了水稻后期抗旱性遗传基础的研究，从而使水稻抗旱育种进展缓慢。本研究利用珍汕97/IRAT109重组自交系群体对水稻后期主要抗旱机制的遗传基础进行了分析，并在大阳两种土壤环境下对水稻后期抗旱性的遗传基础进行初步研究的基础上，对水稻大刚后期抗旱性的机制进行了初步分析。主要结果如下： 1、两亲本比较发现，耐旱性是珍汕97主要的抗旱机制，而早稻亲本IRAT109避旱性(根系、叶片保水能力)强于珍汕97，此外水分分配也是IRAT109适应干旱胁迫的机制之一。 2、对该重组自交系群体(180个系)构建了遗传连锁图，该图谱包含245个SSR标记，12个连锁群，总长为1530cM，相邻标记间平均间距为6.2cM。 3、采用分期播种技术，在不同的光温条件下，定位到9个与抽穗期有关的QTL，它们与控制产量QTL的关系以及与环境互作的分析有助于选育早熟高产、对环境不敏感的品种，为逃旱性在水稻生产上的利用打下基础。 4、用PVC管在孕穗期对RIL群体的各系进行了相同程度的干旱胁迫，将各种可能的抗旱机制加以分离。抗旱系数(相对产量)与抽穗期、地上干物重及大部分根系性状间无显著相关性，说明该试验中逃旱性的影响得到消除，并将避早性的作用加以分离。两年共检测到37个与耐旱性(产量、产量性状的相对值和死叶程度)有关的QTL，与他人定位结果比较也证实了它们主要与耐旱性(渗透调节能力等)有关。对产量、产量性状在对照和干旱胁迫下QTL定位的一致性进行了分析，少数干旱胁迫下表达的QTL与相对值QTL相对应。 5、两年定位了6个与干旱到卷叶的天数(DLR)有关的QTL，相关分析及QTL比较发现，根系下扎速度及干旱诱导根系深度增加量与干旱到卷叶的天数之间呈正相关，而与植株和根系大小之产呈负相关。另外，用PVC管两年定位了71个与最大扎根深度和深层根分布有关的QTL，以及97个与根粗、根总体积(重量)及根茎比有关的QTL。最大扎根深度和深层根分布等根系性状与根粗、根总体积(重量)和根茎比等根系性状相比对环境条件(年度、水分)更为敏感。 6、相关分析和QTL位置比较发现，控制耐旱性和避旱性的染色体区域相对独立，说明耐旱性和避旱性的遗传基础不同，可以在抗旱育种上将二者加以聚合。 7、在错期播种调整抽穗期一致的前提下，分别在粘土和沙土环境下对大田后期更多还原

【Abstract】 Drought especially late season drought is one of the main abiotic constraints in rice production, and the genetic basis of drought resistance in rice is very complex due to different mechanisms mixed together which resulted in slow progress on drought resistance breeding in rice. In this study, a genetic linkage map was constructed for mapping QTLs for drought escaping (via early heading), drought avoidance (mainly via root traits) and tolerance using a RIL population of 180 lines from a cross between an indica lowland rice and upland japonica rice. Genetic analysis of drought resistance at reproductive stage in field with different types of soil was also conducted to find the possible mechanism of late season drought resistance in rice under field conditions. The main results were as follows:1. The comparison of drought resistance between two parents revealed that drought tolerance was the main drought resistance mechanism of the parent Zhenshan 97, whereas for the upland and japonica parent, IRAT109, the ability of drought avoidance (root traits and water keeping ability) was higher than Zhenshan 97, and drought resistance can also be achieved by water distribution in IRAT109.2. A genetic linkage map was constructed based on the data of 245 loci assayed on the 180 individuals by Mapmaker analysis. The map covered a total of 1530cM with an average interval of 6.2cM between adjacent loci.3. Nine QTLs for heading date were detected under four environments with different day-length and temperature. Their relations with yield and the QTL by environment interactions analysis revealed that it is possible to breed rice varieties with early maturing, high yield and unsensitive to environments, which is very important to drought escaping in rice.4. Similar drought stress was applied at same stage (booting to anthesis) on each rice plant grown in PVC pipes on the basis of staggering seeding date in the year 2003 and 2004. Correlation analysis revealed that relative yield (RY, corresponding to drought susceptibility index) had no significant correlation with flowering time, biomass and most of the root traits investigated in two years, suggesting that drought escaping was更多还原