Net work of quantitative trait loci responsible for evolutionary change in rice

广播稻和栽培稻在决定产量和繁殖方法的许多数量性状上存在差异。本研究的目的是利用栽培稻与野生稻品系杂交来鉴定这些数量性状(QTL)，并阐明它们在水稻基因组上的网络。1)QTL分析发现140个分子标记在双亲之间是多态的。对上述组合衍生的125个R6重组自交系(RILs)进行了标记分离调查，构建了连锁图谱。共检测到30多个数量性状，并利用qGENE软件对分子标记和数量性状进行了共分离分析，共检测到22个性状的176个QTL。控制某一性状的QTL广泛分布在不同的染色体上。不同性状的QTL倾向于聚集在12条染色体上的几个特定区域。在标记附近发现了这样的簇，显示出显著的…品种衍生等位基因不能过多2)种子破碎率的选择试验通过F_3代的大量繁殖，建立了上述两个杂交群体。一种是粉碎组(S)，将粉碎在地上的种子收集起来，用来饲养下一代。另一组为非破碎组(NS)，将留在穗上的种子收获后用于培育后代。对所建立的两个F7群体进行了80个RFLP标记和各种数量性状的检测。S处理的品系抽穗较晚，种子休眠较强，再生能力较强。S组与NS组部分RFLP的等位基因频率差异有统计学意义。这些基因大多与水稻种子脱粒的QTL连锁。上述结果提示水稻驯化的可能遗传机制。由人类播种和收获所定义的“耕作”，必须是有利于不破碎植物的强大自然选择。此外，QTL的连锁或基因簇也有助于在驯化过程中形成性状的适应性关联。较少

Wide and cultivated rices differ in many quantitative characters responsible for yielding capacity and propagation method. The objective of this study is to identify loci of those quantitative traits (QTL) and elucidate their network on rice genome using a cross between cultivated rice and a strain of wild rice.1) QTL analysisOne-hundred forty molecular markers were found to be polymorphic between two parents. Segregation of those markers were surveyed among 125 R_6 Recombinant Inbred Lines (RILs) derived from the above cross, and linkage map was constructed. More than 30 quantitative traits were measured in respective RILs, and cosegregation of molecular markers and quantitative traits were analyzed by qGENE.A total of 176 QTLs for 22 traits were detected. QTLs controlling a given trait were widely scattered on different chromosomes. QTLs for different traits tended to cluster on several specific regions of 12 chromosomes. Such clusters were found near the markers which showed signifi … More cant excess of cultivar-derived alleles.2) Selection experiment on seed shatteringTwo hybrid populations of the above cross were established by propagating after F_3 in bulk as follows. One is shattering group (S) in which seeds shattered on the ground were collected and used for raising next generation. The other is non-shattering group (NS) in which seeds remaining on the panicles were harvested and used for raising next generation. Two F_7 populations thus established were examined regarding 80 RFLP markers and various quantitative traits. Lines of S group showed later heading, stronger seed dormancy, stronger regenerating ability than those of NS group. Allele frequencies of some RFLP showed significant difference between S and NS groups. They are mostly linked with QTLs responsible for seed shattering.The above results suggest possible genetic mechanisms of domestication in rice. "Cultivation" defined by seeding and harvesting by man must have worked as strong natural selection favoring non-shattering plants. Further, linkage or gene cluster of QTLs also contributed to forming adaptive association of characters in domestication process. Less