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標題: 玉米第二對染色體短臂的 RFLP 標誌之實體定位
Physical Mapping of RFLP Markers on the Short Arm of Chromosome 2 in Maize
作者: 陳宏銘
Chen, Hong-Ming
關鍵字: Physical mpping
Terminal deficiency
Partial mnosome
RFLP markers
出版社: 分子生物學研究所
摘要: ABSTRACT The r-X1 deletion is an interstitial deficiency located on the long arm of chromosome 10. It induces chromosome breakage at the second mitosis during megasporogenesis. The resulting fragment without centromere is lost from the cell, and the other fragment with centromere remaining in the cell is terminally deficient, called partial monosome (or PM). PM becomes an important tool of physical mapping, because the breakpoints of PMs vary along the length of a chromosome arm. The objective of this research is to use PMs to map physically the RFLP markers on the short arm of maize chromosome 2. Four PMs were produced by the r-X1-carrying plants after crossing with the lg1, gl2 pollen. They were identified, together with complete monosome 2 (or CM), as recessive glossy and ligueless seedling among the F1 progeny. The PMs were differentiated from the CMs by root tip chromosome counts and RFLP analysis. In this research, four PMs were used to physically map six RFLP markers. One of these (P2S4) is proximal to umc53, umc6, umc44, and uaz295 but distal to umc131 and umc135. The three others (P2S1, P2S2, and P2S3) are all proximal to umc53, umc6, umc44, uaz295, and umc131. The map order of four PM breakpoints and six RFLP markers is as follows: telomere (2S)-(umc53, umc6, umc44, and uaz295)-P2S4-umc131-(P2S1, P2S2, and P2S3)-(umc135 and centromere). The physical order of the six markers is consistent with that of Helentjaris's map. But the sequence of umc131 and umc135 is reversed in comparing with the map of Davis et al .
摘 要 玉米的 r-X1 是發生在第十條染色體長臂上中間一小段缺失。它會在胚囊母細胞減數分裂後的第二次有絲分裂時,造成染色體斷裂。在斷裂後,不含中節的染色體片段會從細胞中消失;含中節的染色體片段就會留在細胞中,形成具有末端缺失的部份單染體 (Partial monosome, PM)。這些部份單染體的斷裂點是分散在染色體臂上,此特性使得部份單染體成為染色體實體定位 (也就是缺失定位) 的重要材料。本研究的目的就是利用部份單染體實體定位玉米第二對染色體短臂上的 RFLP 標誌。 四株部份單染體植株是由 r-X1 的玉米與含有隱性 lg1 和 gl2 的花粉進行雜交產生的。它們是從 F1 子代中,先篩選出表現隱性 gl2 和lg1 的植株,再藉由根尖的染色體和RFLP分析來鑑定。 在本論文中,利用四株部份單染體植株將六個 RFLP 標誌實體定位。其中 P2S4 是位於 umc53、umc6、umc44 和 uaz295的內側 (proximal,斷裂點比標誌接近中節),但是在 umc135 和 umc131的外側 (distal,斷裂點比標誌遠離中節)。P2S1、P2S2 和 P2S3 都位於umc53、umc6、umc44、uaz295 和 umc131 的內側。四個部份單染體的斷裂點與六個 RFLP 標誌的順序如下: 2S telomere-(umc53、umc6、umc44 和 uaz295)-P2S4-(umc131)-(P2S1、P2S2 和 P2S3)-(umc135 和 centromere)。上述結果和 Helentjaris 圖譜的標誌順序一致,但與 Davis 等人圖譜相較,umc131 和 umc135 的順序是相反。
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