Naturally occurring autopolyploid species, such as the autotetraploid potato Solanum tuberosum, face a variety of challenges during meiosis. These include proper pairing, recombination and correct segregation of multiple homologous chromosomes, which can form complex multivalent configurations at metaphase I, and in turn alter allelic segregation ratios through double reduction. Here, we present a reference map of meiotic stages in diploid and tetraploid S. tuberosum using fluorescence in situ hybridisation (FISH) to differentiate individual meiotic chromosomes 1 and 2. A diploid-like behaviour at metaphase I involving bivalent configurations was predominant in all three tetraploid varieties. The crossover frequency per bivalent was significantly reduced in the tetraploids compared with a diploid variety, which likely indicates meiotic adaptation to the autotetraploid state. Nevertheless, bivalents were accompanied by a substantial frequency of multivalents, which varied by variety and by chromosome (7–48%). We identified possible sites of synaptic partner switching, leading to multivalent formation, and found potential defects in the polymerisation and/or maintenance of the synaptonemal complex in tetraploids. These findings demonstrate the rise of S. tuberosum as a model for autotetraploid meiotic recombination research and highlight constraints on meiotic chromosome configurations and chiasma frequencies as an important feature of an evolved autotetraploid meiosis.

中文翻译：

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马铃薯减数分裂过程中的品种变异和染色体行为

自然发生的同源多倍体物种，如同源四倍体马铃薯马铃薯，在减数分裂过程中面临着各种挑战。这些包括多个同源染色体的正确配对、重组和正确分离，这些染色体可以在中期 I 形成复杂的多价构型，进而通过双重还原改变等位基因分离率。在这里，我们展示了二倍体和四倍体马铃薯减数分裂阶段的参考图，使用荧光原位杂交 (FISH) 来区分个体减数分裂染色体 1 和 2。中期 I 的二倍体样行为涉及二价构型在所有三个中都占主导地位四倍体品种。与二倍体品种相比，四倍体品种的每二价交叉频率显着降低，这可能表明减数分裂对同源四倍体状态的适应。然而，二价体伴随着大量频率的多价体，其因品种和染色体而异（7-48%）。我们确定了突触伴侣转换的可能位点，导致多价形成，并发现了四倍体中突触复合物聚合和/或维持的潜在缺陷。这些发现证明了马铃薯作为同源四倍体减数分裂重组研究模型的兴起，并强调了对减数分裂染色体配置和交叉频率的限制，这是进化的同源四倍体减数分裂的一个重要特征。我们确定了突触伴侣转换的可能位点，导致多价形成，并发现了四倍体中突触复合物聚合和/或维持的潜在缺陷。这些发现证明了马铃薯作为同源四倍体减数分裂重组研究模型的兴起，并强调了对减数分裂染色体配置和交叉频率的限制，这是进化的同源四倍体减数分裂的一个重要特征。我们确定了突触伴侣转换的可能位点，导致多价形成，并发现了四倍体中突触复合物聚合和/或维持的潜在缺陷。这些发现证明了马铃薯作为同源四倍体减数分裂重组研究模型的兴起，并强调了对减数分裂染色体配置和交叉频率的限制，这是进化的同源四倍体减数分裂的一个重要特征。