Linkage analysis of rice by use of RFLPs (Restriction fragment length polymorphisms).

限制性片段长度多态性（RFLP）表示通过用特异性限制性酶消化产生的基因组DNA片段的长度差异。它们可以作为有用的遗传标记用于遗传分析和育种计划。本研究与农林水产省农业生物资源研究所和北陆农业试验站的RFLP小组合作，以水稻Pst Ⅰ基因组文库中的克隆为探针，利用Southern杂交技术，对水稻的RFLP标记、形态标记基因和同工酶位点进行了连锁定位。用最大似然法分析了籼稻Kasalath与粳稻多遗传标记系FL 134杂交F_2群体（144株）的分离数据。所构建的连锁图包含了12个可能的连锁群。根据形态学和同工酶标记的染色体定位信息，有可能将12个组中的6个分配到它们各自的染色体（根据Nishimura的命名，染色体4、5、6、8、9和11）。为了将其余的RFLP连锁群定位到各自的染色体上，我们进行了杂种初级三体的基因剂量分析和F_2三体分离分析。利用这些分析，将21个RFLP克隆分别定位到特定的染色体上，验证了12个RFLP连锁群与相应染色体的关系，并检测了2个抗白叶枯病基因Xa-1和Xa-2与2个RFLP标记之间的连锁关系。在11号染色体上的排列顺序为lg-Ph-Xa-1-Xa-2-120-102。本文还对RFLP图谱与传统连锁图谱的比较进行了讨论。

Restriction fragment length polymorphisms (RFLPs) represent differences in the length of the fragment of genomic DNA produced by digestion with specific restriction enzymes. They can be used as useful genetic markers in genetic analysis and breeding programs. In this study, linkage mapping was conducted on RFLP markers, morphological marker genes and isozyme loci in rice in collaboration with RFLP groups of National Institute of Agrobiological Resources and Hokuriku Agricultural Experiment Station, Ministry of Agriculture, Forestry and Fishery.RFLPs were detected using clones selected from a Pst I genomic library of rice as DNA probes by Southern analysis. Segregation data in a F_2 population (144plants) from a cross between Kasalath (Indica) and FL134 ( a multiple genetic marker line of Japonica) were analyzed by the maximum likelihood method. The linkage map constructed comprised possible twelve linkage groups of rice. It was possible to assign six of the twelve groups to their respective chromosomes (chromosomes 4, 5, 6, 8, 9 and 11 according to Nishimura's designation) based on the information on chromosomal location of morphological and isozyme markers. In order to assign the rest of the RFLP linkage groups to their respective chromosomes, we performed gene dosage analysis of hybrid primary trisomics and F_2 trisomic segregation analysis. With these analyses, we assigned 21 RFLP clones to specific chromosomes and verified relationship of twelve RFLP linkage groups with the respective chromosomes.We also detected the linkage among two bacterial blight resistance genes, Xa-1 and Xa-2, and two RFLP markers. The arrangement of the loci were lg-Ph-Xa-1-Xa-2-120-102 on chromosome 11. The comparisons of the RFLP and conventional linkage maps were also discussed in this study.