Othmeni Manel, Grewal Surbhi, Hubbart-Edwards Stella, Yang Caiyun, Scholefield Duncan, Ashling Stephen, Yahyaoui Amor, Gustafson Perry, Singh Pawan K, King Ian P, King Julie
Nottingham BBSRC Wheat Research Centre, Division of Plant and Cop Sciences, School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, United Kingdom.
International Maize and Wheat Improvement Center (CIMMYT) Mexico, Mexico City, Mexico.
Front Plant Sci. 2019 Sep 18;10:1110. doi: 10.3389/fpls.2019.01110. eCollection 2019.
The wild relatives of wheat provide an important source of genetic variation for wheat improvement. Much of the work in the past aimed at transferring genetic variation from wild relatives into wheat has relied on the exploitation of the mutant, located on the long arm of chromosome 5B. This mutation allows homologous recombination to occur between chromosomes from related but different genomes, e.g. between the chromosomes of wheat and related chromosomes from a wild relative resulting in the generation of interspecific recombinant chromosomes. However, the mutant also enables recombination to occur between the homologous genomes of wheat, e.g. A/B, A/D, B/D, resulting in the generation of wheat intergenomic recombinant chromosomes. In this work we report on the presence of wheat intergenomic recombinants in the genomic background of hexaploid wheat/ introgression lines. The transfer of genomic rearrangements involving the D-genome through pentaploid crosses provides a strategy by which the D-genome of wheat can be introgressed into durum wheat. Hence, a pentaploid crossing strategy was used to transfer D-genome segments, introgressed with either the A- and/or the B-genome, into the tetraploid background of two durum wheat genotypes Karim and Om Rabi 5 in either the presence or absence of different (2n = 2x = 14, TT) introgressions. Introgressions were monitored in backcross generations to the durum wheat parents multi-color genomic hybridization (mc-GISH). Tetraploid lines carrying homozygous D-genome introgressions, as well as simultaneous homozygous D- and T-genome introgressions, were developed. Introgression lines were characterized Kompetitive Allele-Specific PCR (KASP) markers and multi-color fluorescence hybridization (FISH). Results showed that new wheat sub-genomic translocations were generated at each generation in progeny that carried any chromosome introgression irrespective of the linkage group that the segment was derived from. The highest frequencies of homologous recombination were observed between the A- and the D-genomes. Results indicated that the genotype Karim had a higher tolerance to genomic rearrangements and T-genome introgressions compared to Om Rabi 5. This indicates the importance of the selection of the parental genotype when attempting to transfer/develop introgressions into durum wheat from pentaploid crosses.
小麦的野生近缘种为小麦改良提供了重要的遗传变异来源。过去许多旨在将野生近缘种的遗传变异转移到小麦中的工作都依赖于对位于5B染色体长臂上的突变体的利用。这种突变使得相关但不同基因组的染色体之间能够发生同源重组，例如小麦染色体与野生近缘种的相关染色体之间，从而产生种间重组染色体。然而，该突变体也能使小麦的同源基因组之间发生重组，例如A/B、A/D、B/D，进而产生小麦基因组间重组染色体。在这项研究中，我们报道了在六倍体小麦/渗入系的基因组背景中存在小麦基因组间重组体。通过五倍体杂交转移涉及D基因组的基因组重排提供了一种将小麦D基因组渗入硬粒小麦的策略。因此，采用五倍体杂交策略将与A和/或B基因组渗入的D基因组片段转移到两个硬粒小麦基因型卡里姆（Karim）和奥姆·拉比5（Om Rabi 5）的四倍体背景中，无论是否存在不同的提莫菲维小麦（2n = 2x = 14，TT）渗入。通过多色基因组原位杂交（mc-GISH）在回交后代中监测渗入到硬粒小麦亲本中的情况。培育出了携带纯合D基因组渗入以及同时携带纯合D和T基因组渗入的四倍体系。利用竞争性等位基因特异性PCR（KASP）标记和多色荧光原位杂交（FISH）对渗入系进行了鉴定。结果表明，在携带任何提莫菲维小麦染色体渗入的后代中，每一代都会产生新的小麦亚基因组易位，无论该片段来自哪个连锁群。在A和D基因组之间观察到最高频率的同源重组。结果表明，与奥姆·拉比5相比，卡里姆基因型对基因组重排和T基因组渗入具有更高的耐受性。这表明在尝试通过五倍体杂交将渗入系转移/培育到硬粒小麦中时，选择亲本基因型的重要性。
