Arrieta Mikel, Macaulay Malcolm, Colas Isabelle, Schreiber Miriam, Shaw Paul D, Waugh Robbie, Ramsay Luke
Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom.
Information and Computational Sciences, The James Hutton Institute, Dundee, United Kingdom.
Front Plant Sci. 2021 Nov 12;12:706560. doi: 10.3389/fpls.2021.706560. eCollection 2021.
Plant breeding relies on the meiotic recombination or crossing over to generate the new combinations of the alleles along and among the chromosomes. However, crossing over is constrained in the crops such as barley by a combination of the low frequency and biased distribution. In this study, we attempted to identify the genes that limit the recombination by performing a suppressor screen for the restoration of fertility to the semi-fertile barley mutant (), carrying a mutation in the barley ortholog of (), a member of the MutL-homolog (MLH) family of DNA mismatch repair genes. mutants exhibit reduced recombination and fewer chiasmata, resulting in the loss of obligate crossovers (COs) leading to chromosome mis-segregation. We identified several candidate suppressor lines and confirmed their restored fertility in an background in the subsequent generations. We focus on one of the candidate suppressor lines, , which showed the most complete restoration of fertility. We characterized this line by using a target-sequence enrichment and sequencing (TENSEQ) capture array representing barley orthologs of 46 meiotic genes. We found that contained a C/T change in the anti-CO gene resulting in the substitution of a non-polar glycine to a polar aspartic acid (G700D) amino acid in the conserved helicase domain. Single nucleotide polymorphism (SNP) genotyping of F populations revealed a significant increase in the recombination frequency in lines with in the background that was associated with the restoration of fertility. The genotyping also indicated that there was nearly double the recombination levels in homozygous lines compared to the wild type (WT). However, we did not observe any significant change in the distribution of CO events. Our results confirm the anti-CO role of in a large genome cereal and establish the possibility of testing the utility of increasing recombination in the context of traditional crop improvement.
植物育种依赖于减数分裂重组或交叉互换，以在染色体上及染色体间产生等位基因的新组合。然而，在大麦等作物中，交叉互换受到低频和分布偏倚的限制。在本研究中，我们试图通过对半育大麦突变体（）进行抑制子筛选来鉴定限制重组的基因，该突变体在大麦直系同源基因（）中发生了突变，（）是DNA错配修复基因MutL同源物（MLH）家族的成员。突变体表现出重组减少和交叉点减少，导致必需交叉互换（CO）丧失，进而导致染色体错分离。我们鉴定了几个候选抑制子系，并在后续世代的背景中证实了它们恢复的育性。我们聚焦于其中一个候选抑制子系，，它表现出最完全的育性恢复。我们通过使用代表46个减数分裂基因大麦直系同源物的靶序列富集和测序（TENSEQ）捕获阵列对该系进行了表征。我们发现，在抗CO基因中含有一个C/T变化，导致在保守解旋酶结构域中一个非极性甘氨酸被极性天冬氨酸（G700D）取代。F群体的单核苷酸多态性（SNP）基因分型显示，在背景中具有的系中重组频率显著增加，这与育性恢复相关。基因分型还表明，纯合系中的重组水平几乎是野生型（WT）的两倍。然而，我们没有观察到CO事件分布的任何显著变化。我们的结果证实了在大基因组谷物中的抗CO作用，并确立了在传统作物改良背景下测试增加重组效用的可能性。
