Physical Mapping of A-A Translocation Breakpoints and RFLP Markers in Maize

玉米的r-X1缺失位於第十條染色體的長臂，該缺失會誘導染色體的不分離(nondisjunction)，產生單染體(complete monosome, CM)。同時也會造成低頻率的染色體斷裂，斷裂後帶有中節(centromere)的染色體片段會留存於細胞中，成為部份單染體(partial monosome, PM)。 本論文的目的是利用r-X1缺失系統，誘導A-A易位染色體的CM與PM，進而標定RFLP標誌與易位染色體斷裂點的位置。CM與PM的取得，是以帶有A-A易位染色體與r-X1缺失的W22品系玉米為母本，與隱性植株(基因座位在易位的染色體上)雜交。此雜交產生的F1子代中，大多數表現預期的顯性外表型，少數表現隱性性狀，並缺失了母本的顯性基因。換言之，r-X1移除了父本隱性基因的覆蓋。有107株隱性植株被篩選出來，其中61株CM和6株PM，利用這些材料，標定出易位染色體 T5-6(6522)的其中一個斷裂點介於第六對染色體長臂的umc21 到 umc132a區域，另一個斷裂點位npi409的遠側端。The r-X1 deletion in maize is a small intercalary deficiency located in the long arm of chromosome 10. The r-X1 deletion induces chromosome nondisjunction and formation of complete monosome (CM). It also generates a low frequency of chromosome breakage. The resulting fragment carrying the centromere is retained in the cell and become a terminal deficiency called partial monosome (PM). This thesis is aimed to isolate CMs and PMs and to use them for physical mapping of RFLP markers and translocation breakpoints. The experimental design is to cross a stock carrying both the r-X1 deletion and A-A translocations with a recessive marker located on one of the translocated chromosomes. The resulting F1 progeny expressed mainly the expected dominant phenotype and a low frequency of recessive phenotype, which are deficient for the maternal dominant allele. In other words, paternal recessive allele is uncovered by r-X1. Of 107 recessive progenies isolated, 61 are CMs and 6 are PMs. Using these materials, one breakpoint of T5-6(6522) was mapped in the umc21-umc132a region on the long arm of chromosome 6, and the other was distal with npi409.目錄 中文摘要 1 英文摘要 2 壹、 前言3 貳、 前人研究5 一、 玉米A-A易位染色體5 二、 r-X1缺失的特性7 三、 遺傳標誌之實體定位11 參、 材料與方法13 一、 遺傳材料13 二、 RFLP標誌15 三、 研究方法16 肆、 結果22 一、 F1突變株的發生頻率22 二、 Py1基因座的實體定位22 三、 T5-6(6522)易位染色體斷裂點與RFLP標誌之定位23 伍、 討論24 一、 F1突變株的發生頻率24 二、 Py1基因座的實體定位26 三、 RFLP標誌之定位27 陸、 參考文獻28 圖表 3