Friebe B, Kynast R G, Gill B S
Wheat Genetics Resources Center, Department of Plant Pathology, Throckmorton Plant Sciences Center, Kansas State University, Manhattan 66506-5502, USA.
Chromosome Res. 2000;8(6):501-11. doi: 10.1023/a:1009219722418.
The gametocidal factor on the Aegilops cylindrica chromosome 2Cc was used to induce and analyze the nature of chromosomal rearrangements in rye chromosomes added to wheat. For this purpose we isolated plants disomic for a given rye chromosome and monosomic for 2Cc and analyzed their progenies cytologically. Rearranged rye chromosomes were identified in 7% of the progenies and consisted of rye deficiencies (4.6%), wheat rye dicentric and rye ring chromosomes (1.8%), and terminal translocations (0.6%). The dicentric and ring chromosomes initiated breakage-fusion-bridge cycles (BFB) that ceased within a few weeks after germination as the result of chromosome healing. Of 56 rye deficiencies identified, after backcrossing and selfing, only 33 were recovered in either homozygous or heterozygous condition covering all rye chromosomes except 7R. The low recovery rate is probably caused by the presence of multiple rearrangements induced in the wheat genome that resulted in poor plant vigor and seed set, low transmission, and an underestimation of the frequency of wheat rye dicentric chromosomes. Genomic in-situ hybridization (GISH) analysis of the 33 recovered rye deficiencies revealed that 30 resulted from a single break in one chromosome arm followed by the loss of the segment distal to the breakpoint. Only three had a wheat segment attached distal to the breakpoint. Although some of the Gc-induced rye rearrangements were derived from BFB cycles, all of the recovered rye rearrangements were simple in structure. The healing of the broken chromosome ends was achieved either by the de-novo addition of telomeric repeats leading to deficiencies and telocentric chromosomes or by the fusion with other broken ends in the form of stable monocentric terminal translocation chromosomes.
利用圆柱山羊草2Cc染色体上的杀配子因子诱导并分析添加到小麦中的黑麦染色体的染色体重排性质。为此，我们分离出了对于某一特定黑麦染色体为二体且对于2Cc为单体的植株，并对其后代进行了细胞学分析。在7%的后代中鉴定出了重排的黑麦染色体，包括黑麦缺失（4.6%）、小麦-黑麦双着丝粒和黑麦环状染色体（1.8%）以及末端易位（0.6%）。双着丝粒和环状染色体引发了断裂-融合-桥循环（BFB），由于染色体修复，这些循环在萌发后几周内停止。在鉴定出的56个黑麦缺失中，经过回交和自交后，只有33个以纯合或杂合状态得以恢复，覆盖了除7R之外的所有黑麦染色体。恢复率低可能是由于小麦基因组中诱导产生的多重重排导致植株活力和结实率低、传递率低以及对小麦-黑麦双着丝粒染色体频率的低估。对33个恢复的黑麦缺失进行基因组原位杂交（GISH）分析表明，30个是由一条染色体臂上的单个断裂导致断点远端片段丢失所致。只有3个在断点远端附着有小麦片段。虽然一些Gc诱导的黑麦重排源自BFB循环，但所有恢复的黑麦重排结构都很简单。断裂染色体末端的修复要么是通过端粒重复序列的重新添加导致缺失和端着丝粒染色体，要么是通过与其他断裂末端融合形成稳定的单着丝粒末端易位染色体。
