Despite possessing related ancestral genomes, hexaploid wheat behaves as a diploid during meiosis. The wheat Ph1 locus promotes accurate synapsis and crossover of homologous chromosomes. Interspecific hybrids between wheat and wild relatives are exploited by breeders to introgress important traits from wild relatives into wheat, although in hybrids between hexaploid wheat and wild relatives, which possess only homoeologues, crossovers do not take place during meiosis at metaphase I. However, in hybrids between Ph1 deletion mutants and wild relatives, crossovers do take place. A single Ph1 deletion (ph1b) mutant has been exploited for the last 40 years for this activity. We show here that chemically induced mutant lines, selected for a mutation in TaZIP4-B2 within the Ph1 locus, exhibit high levels of homoeologous crossovers when crossed with wild relatives. Tazip4-B2 mutant lines may be more stable over multiple generations, as multivalents causing accumulation of chromosome translocations are less frequent. Exploitation of such Tazip4-B2 mutants, rather than mutants with whole Ph1 locus deletions, may therefore improve introgression of wild relative chromosome segments into wheat.

中文翻译：

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利用小麦 Ph1 基因座内的 ZIP4 同源物已经确定了两个在小麦-野生近缘杂种中表现出同源交叉的品系。

尽管拥有相关的祖先基因组，六倍体小麦在减数分裂过程中表现为二倍体。小麦 Ph1 基因座促进同源染色体的准确突触和交叉。育种者利用小麦和野生近缘种之间的种间杂种将重要性状从野生近缘种渗入小麦，尽管在仅具有同源物的六倍体小麦和野生近缘种之间的杂交种中，在减数分裂中期 I 期间不会发生交叉。然而，在Ph1 缺失突变体和野生近缘种之间的杂种，交叉确实发生。在过去的 40 年中，人们利用了一个单一的 Ph1 缺失 (ph1b) 突变体来进行这项活动。我们在这里展示了化学诱导的突变系，选择用于 Ph1 基因座内 TaZIP4-B2 中的突变，与野生近缘种杂交时表现出高水平的同源杂交。Tazip4-B2 突变系可能在多代后更稳定，因为导致染色体易位积累的多价基因不太常见。因此，利用这种 Tazip4-B2 突变体，而不是具有整个 Ph1 基因座缺失的突变体，可以改善野生相关染色体片段向小麦的基因渗入。