Molecular genetics of a mutator in rice

用γ射线辐照水稻品种金宝津种子，同时诱发了一个突变体和一个隐性的细长颖基因（SG）。SG基因回复突变后激活的突变子可在数量性状和质量性状的多个位点上引起不同类型的突变。本研究通过RFLP和RAPD分析，寻找与SG基因紧密连锁的DNA标记，并对SG基因和突变体基因进行分离和分子结构分析，发现SG基因与位于第7染色体上的rfs基因紧密连锁。这一结果允许估计20和152两个RFLP标记与SG位点连锁。通过使用这些连锁关系，将确定更紧密连锁的RFLP标记。对突变体诱导的下垂湿叶基因（drp-m）的RFLP连锁分析表明，drp-m与位于第9染色体上的RFLP标记385紧密连锁。这有力地表明drp-m位点是drp-2位点。利用玉米花色素苷合成基因、Al基因和Cl基因的cDNA，对水稻有色系和非有色系进行了RFLP分析。这表明，突变体诱导的着色基因可以通过使用这些cDNA作为探针分离。

A mutaor and a recessive slender-glume gene(SG) were simultaneously induced by gamma-ray irradiation of seeds of a rice variety Gimbozu. The mutator which is activated by a reverse mutation of SG to normal-glume gene induces various types of mutations in many loci of both quantitative and qualitative characters. In this study, RFLP-analysis and RAPD-analysis were carried out to find out the DNA maker closely linked with the SG and the mutator-induced mutant genes for isolating these genes and elucidating their molecular structurers.The conventional linkage analysis for SG showed that SG locus was closely linked with rfs locus, which is located on seventh chromosome. This result allowed to estimate that two RFLP makers of 20 and 152 were linked with SG locus. More closely linked RFLP makers will be identified by using these linkage relationships. RAPD makers for SG locus were not found out in this study.The RFLP linkage analysis for mutator-induced drooping- wet-leaf gene(drp-m) showed that drp-m locus was closely linked with RFLP maker 385, which is located on ninth chromosome. This strongly suggests that drp-m locus is drp-2 locus. By using cDNA of anthocyanin-synthetic genes derived from maize, Al and Cl, RFLP could be detected between colored and non-colored lines of rice. This indicates that mutator-induced coloring gene can be isolated by the use of these cDNAs as probes.