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標題: 以RFLP分析玉米第八對染色體之尖端缺失
Characterization of terminal deficiency associated with the long arm of chromosome 8 in maize
作者: 張士鼎
Chang, Shih-Ting
關鍵字: maize
r-X1 deletion
partial monosome
r-X1 缺失
出版社: 植物學系
摘要: 玉米的r-X1缺失(deficiency)最早由L.J.Stadler用X-ray誘導獲得,為一 無法由顯微鏡觀察之染色體缺失。帶此缺失的第10條染色體不能經由父本 傳遞,只能藉母本傳給子代。此缺失能在胚囊發生過程(mega- gametogenesis)中引起染色體不分離(nondisjunction)導致單染體 (complete monosomy,簡稱CM)及部分單染體(partial monosomy,簡稱 PM)子代的發生。在玉米第2、8對染色體上均曾證實有PM的發生。本論文 的目的是利用已知位置之限制片段多形性(restriction fragment length polymorphism,簡稱RFLP)標誌(markers)標定第8條染色體PM的斷 裂位置,並用這些PM測定這條染色體長臂上現有的RFLP標誌圖譜是否正確 。本研究利用位於第八條染色體長臂(簡稱8L)末端之japonica(j1)隱性基 因篩選到三株PM植株(3/982=3.1%),加上先前獲得的七株共十株PM,其中 因故損失一株,故共取九株PM利用RFLP標誌進行分析。結果顯示現有九株 PMs斷點並不一致,分佈在第8條染色體長臂四個不同區域。其中五株斷點 位於 RFLP標誌umc103A與umc12(umc93)之間,三株位於RFLP標誌umc12( umc93)與 umc30之間,最遠有一株斷於umc30與j1基因座(locus)之間。利 用這些PM實體標定現有8L的RFLP標誌的次序,所得結果與原來聯鎖圖譜大 致一致。同時也把第8條染色體中節位置侷限於umc103A附近。
The r-X1 deficiency in maize was first isolated with X irradiation by L.J.Stadler. It is a submicroscopic, intercalary deficiency located on chromosome 10. It is transmitted to progeny only through the maternal plant. It can induce the formation of monosomic (or CM) and partial monosomic (or PM) progeny as the result of chromosome nondisjunction and breakage that occur during megagametogenesis. The purpose of this study is to map the breakpoints of paitial monosome 8s by using the well-mapped RFLP (restriction fragment length polymorphism) markers, and to use them to reevaluate the accuracy of current RFLP linkage map of the long arm chromosome 8. In this study, three partial monosomic plants were obtained, one of them had been lost. The remaining two in addition to seven PMs obtained earlier were used for RFLP analysis. The result shows that the breakpoints of these nine PMs are not located at the same chromosome location. Five of them are located in the 103A - umc12 (umc93) region, and three others are located in the umc12 (umc93) - umc30 rejion. The last one is located in the region between umc30 and j1 locus. The physical map of RFLP markers on the long arm of chromosome 8 as constructed by using these nine partial monosomes is consistent with the conventional linkage map: no rearranged gene order is observed. This study also map centromere of chromosome 8 to the chromosome region close to umc 103A.
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