Chromosomal inversion is an important structural variation that usually suppresses recombination and is critical for key genotype fixation. In a previous study, an 11.47 Mb recombination suppression region was identified in the yellow–green leaf locus BoYgl-1 on chromosome 1, but the cause of recombination suppression is still unclear. In this study, chlorophyll and carotenoid contents were found to be significantly decreased in the yellow–green leaf mutant YL-1. Genome assembly and comparative analysis revealed that two large inversions in YL-1 were responsible for the severe recombination suppression in the BoYgl-1 locus. Analyses with inversion-specific markers revealed that the inversions were present in 44 (including all wild cabbage; INV1 and INV2) of 195 cabbage inbred lines and 15 (INV1) ornamental kale inbred lines, indicating that the wild cabbage may be the ancestor of other domesticated cabbage. Analyses with inversion-correlated markers revealed that the genotypes of CoINV1, CoINV2 and CoINV3 were highly correlated with INV1 and INV2, indicating that INVs could fix the key genotypes of the involved region. In addition, a 5.87 Mb assembly inversion was identified at the BoYgl-1 locus in the TO1000 genome by genome comparative analysis. This study provides new insight into the recombination suppression mechanism of chromosomal inversion and the application of genome fragment fixation in cabbage breeding.

中文翻译：

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两个大的倒位严重抑制重组，对于卷心菜（Brassica oleracea L. var.capitalata）关键基因型固定至关重要

染色体倒位是一种重要的结构变异，通常会抑制重组，对于关键基因型固定至关重要。此前的研究在1号染色体黄绿叶位点BoYgl-1中发现了一个11.47 Mb的重组抑制区域，但重组抑制的原因仍不清楚。在本研究中，发现黄绿叶突变体YL-1的叶绿素和类胡萝卜素含量显着降低。基因组组装和比较分析表明，YL-1 中的两个大倒位导致了 BoYgl-1 基因座的严重重组抑制。对倒位特异性标记的分析显示，倒位存在于 195 个甘蓝自交系中的 44 个（包括所有野生甘蓝；INV1 和 INV2）和 15 个（INV1）观赏羽衣甘蓝自交系中，这表明野生甘蓝可能是其他野生甘蓝的祖先。驯化的卷心菜。对倒位相关标记的分析表明，CoINV1、CoINV2和CoINV3的基因型与INV1和INV2高度相关，表明INV可以修复相关区域的关键基因型。此外，通过基因组比较分析，在 TO1000 基因组的 BoYgl-1 基因座上发现了 5.87 Mb 的组装倒位。该研究为染色体倒位的重组抑制机制以及基因组片段固定在甘蓝育种中的应用提供了新的见解。