To investigate chromosome differentiation of genome A and B between common wheat and wild emmer wheat ( Triticum turgidum var. dicoccoides (Koern.) Bowden), the authors conducted a RFLP analysis of the two species using 153 genomic, cDNA and chromosome-specific probes. 75.8% of the probes had detected hybridization polymorphism in at least one of the five restriction enzymes. However, the polymorphic probes were unevenly distributed among different homoeologous groups, between different genomes and in different regions of a single chromosome. Homoeologous group 1 possessed the highest level of polymorphism (96.2%), followed by group 6 and 2 (84.6% and 82.1% respectively). In contrast, only 60%-67% of probes of the other four groups was polymorphic. In most groups the number of probes capable of detecting B chromosome polymorphism was slightly higher than that revealing A chromosome difference (totally 51.8% vs 43.1%). In a single chromosome, RFLP was predominant in the distal region (65.1%) and showed a decreasing trend from the proximal (46.2%) to the pericentric (42.4%) regions. The results suggest that there exists a substantial amount of DNA polymorphism between the A and B chromosomes of common wheat and those of wild emmer wheat, indicating that a considerable degree of genetic differentiation has taken place in the A and B genoms of two species during evolution from wild emmer to common wheat. The extent of the genetic differentiation may vary among different homoeologous groups, between A and B chromosomes and in different regions of individual chromosome.
利用RFLP 揭示普通小麦与野生二粒小麦间A 和B 组染色体的遗传分化
戎均康1* 刘宝2**
（1. 浙江大学农学系，杭州310029；2. 东北师范大学细胞与遗传研究所，长春130024）
摘要：普通小麦是栽培二粒小麦 (Triticumturgidum var.dicoccum ShrankexSch櫣ｂｌｅｒ)与粗山羊草 (T .tauschiiCoss .)天然杂交并自然加倍的产物 ,而栽培二粒小麦是由野生二粒小麦 (T .turgidumvar.dicoccoides (Koern .)Bowden)进化而来的。从野生二粒小麦到普通小麦的进化过程中其遗传物质可能发生了许多变化。以普通小麦_野生二粒小麦染色体臂置换系为材料 ,研究了普通小麦与野生二粒小麦间的限制性片段长度多态性 (RFLP) ,以揭示此二物种之间A和B组染色体的遗传分化。结果表明 ,两物种的A和B染色体均存在很大的差异。在所研究的 15 3个包括基因组、cDNA和染色体专化序列在内的探针中 ,75 .8%的探针至少在所用的 5种限制性内切酶中的一种具有多态性 ,但是这种多态性在A和B染色体上的分布是不均匀的。就同源群 (Homoeologousgroup)来说 ,第一群具有最高的多态性 (96 .2 % ) ;第六和二次之 (分别为 84.6 %和 82 .1% ) ;其余 4个群最低 (约在 6 0 %～ 6 7%之间 )。在大多数的群中 ,B组染色体通常比相应的A组染色体具有较高的多态性。所有B组染色体的多态性频率为 5 1.8% ,而A组染色体为 43.1%。位于染色体末端的探针比染色体中部和着丝点周围的探针显示较高的多态性 ,三者的多态性频率分别为 6 5 .1%、46 .2%和42.4%。以上结果表明，上述二物种在DNA 分子水平上已存在很大的遗传分化。对这些遗传分化发生的时间和机制进行了讨论。
关键词： 小麦；染色体臂置换系；遗传分化；限制性片段长度多态性；物种进化
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