以異源染色體添加系從事菸草的基因定位

Abstract

以含二套N. plumbaginifolia (2n＝20)染色體及一套N . sylvestris （n＝12)染色體的異源三倍體體細胞雜種（ 2n＝32 ）與二倍體N. plumbaginifolia 回交一與二次，得到 93株含二套N. plumbaginifolia及一條N . sylvestris 染色體的異源單染色體添加植株。根據外形這些植株可分成 13 組 ，每組植株的外形各有特徵。以 61 個探針進行限制?片段長度多型性分析，有 13 個探針在所有的染色體添加植株均偵測不到N . sylvestris的 DNA ，其餘48 個探針（包括 rDNA 及 NR基因）將染色體添加植株分為 9 個正常的添加系，及 4 個染色體轉座或丟失的變異型添加系。正常的添加系中有四個添加系的N . sylvestris．染色體已鑑定為 sat-1 、 sat-2 、 sat-3 及第 12 條短的中位中節染色體，另 5 個系的染色體未鑑定出，只歸為N . sylvestris的 A 、B 及C 組染色體。其中有一株在顯微鏡下觀察到染色體丟失。另外有一植株外形特殊，但在染色體觀察與限制?片段長度多型性分析並沒有發現變異。此外，在體細胞雜種中也偵測到N. plumbaginifolia的 DNA 變異。本論文並發現， sat-3 染色體的 rDNA 在二倍體N . sylvestris中不表現，但在染色體添加植株中則可偵測到其活性。

An allotriploid hybrid (genomes PPS) obtained from protoplast fusion between haploid Nicotiana plumbaginifolia (P, n= 10) and haploid N. sylvestris (S, n=12) was backcrossed to diploid N. plumbaginifolia to establish monosomic chromosome addition lines. A total of 93 2n=21 plants, each containing a 2n chromosome complement of N. plumbginifolia and a single chromosome of N. sylvestris, appeared in the BC1 and BC2 generations. The 2n=21 plants could be classified into 13 groups based on morphological characteristics. The N. sylvestris chromosomes in the 2n=21 plants were determinated by RFLP markers and karyotype analysis. Of the 61 RFLP markers analysed, 13 could not detect N. sylvestris DNA bands in the 2n=21 plants, whereas the remaining 48 markers (including rRNA and NR genes) identified 9 normal and 4 aberrant lines. The N. sylvestris chromosomes in the normal lines were chromosomes 9 (sat-1), 10 (sat-2), 11(sat-3), 12, one of the A group, one of B group, and three of the C group, respectively. The N. sylvestris chromosomes in the aberrant lines could not be identified with certainty, but presumably they were translocated or deleted chromosomes. One morphologically distinct 2n=21 plant showed no chromosomal and DNA changes judged by karyotype and RFLP analysis. The rRNA genes in sat-3 chromosome do not usually express in diploid N. sylvestris, but are active when added to the genetic background of diploid N. plumbaginifolia