【作者】 华玉伟；

【导师】 李再云；

【作者基本信息】 华中农业大学 ， 作物遗传育种， 2005， 博士

【摘要】 在植物远缘杂交中已报道了假配生殖、半配生殖、不减数配子、染色体消除、染色体加倍、亲本染色体在空间上的分开排列等几种特殊染色体的行为，特别是最近在芸薹属(Brassica) 栽培种与诸葛菜(Orychophragmus violaceus(L．)O．E．Schulz．，2n=24)的属间杂交中观察到亲本染色体组在杂种细胞分裂中的完全和部分分开现象。为了进一步研究染色体组分开现象发生的机制、为该现象的发生提供分子和分子细胞学证据，本研究重新合成了三个芸薹属栽培四倍体种甘蓝型油菜(Brassica napus L．，2n=38，染色体组为AACC)、芥菜型油菜(B．juncea(L．)Czern & Coss．，2n=36，AABB)和埃塞俄比亚芥(B．carinata A．Braun，2n=34，BBCC)与诸葛菜的属间杂种，并利用基因组原位杂交(Genomic in situ hybridization，GISH)和扩增片段长度多态性(Amplified fragment length polymorphism，AFLP)方法对这些杂种及后代的基因组及染色体组成进行了分析。主要结果如下： 1、在埃塞俄比亚芥(GO-7)×诸葛菜的组合中，获得来自25个胚的F1再生植株。根据子房染色体数的数目和形态观察，这些F1植株可分为三类：第一类2n=24-35、第二类2n=20-34和第三类2n=17-34。所有F1植株的子房细胞具有不同数目的染色体，即F1植株为混倍体，但所有F1植株内没有超过34条染色体的细胞，且以2n=34的细胞为主，只是第一类中的唯一植株的部分细胞具有2n=35，但多出的一条为小染色体；大部分花粉细胞(PMCs)在终变期具有17个二价体和在后期Ⅰ表现17：17的分离，这与母本‘GO-7’的减数分裂行为相似。第一类唯一植株的部分PMCs也具有2n=35，在终变期形成17Ⅱ+1Ⅰ，在后期Ⅰ以17：17并附加1到2条落后染色体的方式分离，即小染色体以单价体形式出现或在后期落后与提前分裂。用黑芥(B．nigra(L．)Koch，2n=16，BB；埃塞俄比亚芥的祖先种之一)和诸葛菜基因组DNA的探针同时分析了22个F1单株中具有不同染色体数目的子房细胞，结果表明在具有不同染色体数的细胞中没有整条诸葛菜染色体，而在所有2n=34和35的细胞中都检测到了16条来自黑芥B基因组的染色体，而在2n＜34的一部分细胞中同样检测到了16条B基因组染色体；另一部分2n＜34的细胞中虽然只检测到了部分B基因组的染色体，但在这些细胞中来自埃塞俄比亚芥的另一个祖先种甘蓝(B．oleracea L．，2n=18，CC)C基因组染色体的丢失的频率要高于B基因组染色体。同样，在PMCs中也未检测出整条诸葛菜的染色体。所有具有17和16个二价体的更多还原

【Abstract】 Several abnormal chromosome behaviors in plant wide crosses have been reported, such as pseudogamy, semigamy, chromosome doubling, chromosme elimination, unreduced gametes and spatial separation of parental gemomes, especially the separation of parental genomes during the mitotic and meiotic divisions of the hybrid cells was proposed in the intergeneric hybridizations between the cultivated Brassica species and Orychophragmus violaceus （L.） O. E. Schulz. （2n=24）. In contiuaiton of these studies, the hybrids of O. violaceus with Brassica napus L. （2n=38, genomes AACC）、 B. juncea （L.） Czern & Coss. （2n=36, AABB） and B. carinata A. Braun （2n=34, BBCC） were obtained again and investigated by the methods of genomic in situ hybridization （GISH） and amplified fragment length polymorphisms （AFLP）. The results were described as follows.1、In B. carinata （GO-7） × O. violaceus cross, F₁ plants from 25 immature embryos were obtained following embryo rescue and were classified into three types according to their chromosome numbers in ovary cells and phenotypic characters. All the F₁ plants with high fertility resembled closely to B. carinata in morphological attributes and were mixoploids with 2n chromosome numbers ranging from 17-35, however, 34 same as in B. carinata being the most frequent in ovary and pollen mother cells. GISH clearly identified 16 chromosomes of B. nigra in ovary cells and PMCs with 2n=34 and 35. However, no O. violaceus chromosome was detected, indicating the presence of intact B. carinata genome and elimination of entire O. violaceus genome. However, some AFLP bands specific for O. violaceus, deleted in B. carinata and novel for the two parents were detected in the leaves. Cells with fewer than 34 chromosomes had lost some B. oleracea chromosomes. F₂ plants were predominantly liked B. carinata but some contained O. violaceus characters.2、 B. napus × O. violaceus cross was repeated with embryo rescue. All F1 plants except one B. napus haploid （2n=19） were mixploids （2n=17-39 in ovaries） with 2n=31, 37, 38, 39 as the maximal chromosome numbers in individuals, but higher numbers appeared in pollen mother cells （PMCs） and only one chromosome and one chromosome segment of 0. violaceus were detected in low frequency in some PMCs and ovary cells （2n=37, 38, 39） by GISH analysis. These chromosome numbers and complements in these mixoploids were attributed to the chromosome additions, substitutions between the genomes from更多还原