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

限制性内切片段长度多态性（RFLPs）是由特定的限制性内切酶酶切产生的基因组DNA片段长度的差异。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研究组合作，对水稻的RFLP标记、形态标记基因和同工酶位点进行连锁定位。从水稻Pst I基因组文库中选择克隆作为DNA探针，采用Southern分析法检测RFLPs。采用极大似然法对籼稻卡萨拉斯（Kasalath）与粳稻FL134（多遗传标记系）杂交F_2群体（144株）的分离数据进行了分析。构建的水稻连锁图谱包括12个可能的连锁群。根据形态学和同工酶标记的染色体位置信息，可以将12个类群中的6个分配到各自的染色体上（根据西村的命名，第4、5、6、8、9和11号染色体）。为了将其余的RFLP连锁组分配到各自的染色体上，我们进行了杂交初级三体的基因剂量分析和F_2三体分离分析。通过这些分析，我们将21个RFLP克隆分配到特定的染色体上，并验证了12个RFLP连锁群与各自染色体的关系。我们还检测到两个抗白叶枯病基因Xa-1和Xa-2与两个RFLP标记之间的连锁。基因座的排列为11号染色体上的lg-Ph-Xa-1-Xa-2-120-102。本研究还讨论了RFLP与传统连锁图谱的比较。

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.