Plant Breeding Department, University of Bonn, Bonn 53115, Germany.
Department of Plant Breeding, Justus Liebig University, Giessen 35392, Germany.
G3 (Bethesda). 2023 Aug 9;13(8). doi: 10.1093/g3journal/jkad136.
Established allopolyploids are known to be genomically stable and fertile. However, in contrast, most newly resynthesized allopolyploids are infertile and meiotically unstable. Identifying the genetic factors responsible for genome stability in newly formed allopolyploid is key to understanding how 2 genomes come together to form a species. One hypothesis is that established allopolyploids may have inherited specific alleles from their diploid progenitors which conferred meiotic stability. Resynthesized Brassica napus lines are often unstable and infertile, unlike B. napus cultivars. We tested this hypothesis by characterizing 41 resynthesized B. napus lines produced by crosses between 8 Brassica rapa and 8 Brassica oleracea lines for copy number variation resulting from nonhomologous recombination events and fertility. We resequenced 8 B. rapa and 5 B. oleracea parent accessions and analyzed 19 resynthesized lines for allelic variation in a list of meiosis gene homologs. SNP genotyping was performed using the Illumina Infinium Brassica 60K array for 3 individuals per line. Self-pollinated seed set and genome stability (number of copy number variants) were significantly affected by the interaction between both B. rapa and B. oleracea parental genotypes. We identified 13 putative meiosis gene candidates which were significantly associated with frequency of copy number variants and which contained putatively harmful mutations in meiosis gene haplotypes for further investigation. Our results support the hypothesis that allelic variants inherited from parental genotypes affect genome stability and fertility in resynthesized rapeseed.
已确立的异源多倍体被认为具有基因组稳定性和可育性。然而，与之相反的是，大多数新合成的异源多倍体是不育的，减数分裂不稳定的。确定新形成的异源多倍体中导致基因组稳定性的遗传因素是理解两个基因组如何融合形成一个物种的关键。一种假设是，已确立的异源多倍体可能从其二倍体祖先那里继承了特定的等位基因，这些等位基因赋予了减数分裂稳定性。合成的甘蓝型油菜品系通常不稳定且不育，与甘蓝型油菜品种不同。我们通过对 8 个芸薹属白菜和 8 个芸薹属甘蓝杂交产生的 41 个合成甘蓝型油菜品系进行非同源重组事件和育性导致的拷贝数变异的特征分析来检验这一假说。我们对 8 个芸薹属白菜和 5 个芸薹属甘蓝亲本进行了重测序，并对 19 个合成品系中减数分裂基因同源物的等位基因变异进行了分析。使用 Illumina Infinium Brassica 60K 阵列对每个品系的 3 个个体进行 SNP 基因分型。自交结实率和基因组稳定性（拷贝数变异数量）显著受到芸薹属白菜和芸薹属甘蓝亲本基因型相互作用的影响。我们鉴定了 13 个可能的减数分裂基因候选基因，这些基因与拷贝数变异的频率显著相关，并且在减数分裂基因单倍型中包含潜在有害的突变，需要进一步研究。我们的结果支持这样的假设，即从亲本基因型中遗传的等位基因变体影响合成油菜的基因组稳定性和育性。
