Potato is a heterozygous autotetraploid crop propagated as tubers. Diploid potatoes, which are mostly self-incompatible due to gametophytic self-incompatibility, are often used to reduce genetic complexity. The discovery of the S locus inhibitor (Sli) gene has created a way to develop diploid inbred lines and perform F1 hybrid breeding in potato. However, residual heterozygosity found in advanced-generation selfed progenies has posed the question of whether a minimum level of heterozygosity is necessary to maintain self-fertility. We continued selfing and finally identified a highly homozygous diploid potato among tenth-generation selfed progeny, which was homozygous at all 18,579 genome-wide single nucleotide polymorphism (SNP) markers surveyed. The S10 plants suffered severe inbreeding depression in terms of fertility and vigor, showing a small number of mature flowers and extremely slow growth. Although asexual techniques such as anther culture followed by chromosome doubling can result in completely homozygous diploid potatoes, all previously derived plants were male sterile. In contrast, continuous selfing using Sli swept out all lethal alleles and selected for self-fertility, which generated a highly homozygous diploid potato retaining male and female fertility and tuberization ability under long days.

中文翻译：

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使用 S 位点抑制剂 (Sli) 基因创建高度纯合的二倍体马铃薯

马铃薯是作为块茎繁殖的杂合四倍体作物。由于配子体自交不亲和，二倍体马铃薯大多是自交不交的，通常用于降低遗传复杂性。S 基因座抑制因子 (Sli) 基因的发现为开发二倍体自交系和在马铃薯中进行 F1 杂交育种开辟了道路。然而，在高级自交后代中发现的残留杂合性提出了一个问题，即是否需要最低水平的杂合性来维持自我生育能力。我们继续自交，最终在第十代自交后代中鉴定出一个高度纯合的二倍体马铃薯，在调查的所有 18,579 个全基因组单核苷酸多态性 (SNP) 标记中都是纯合的。S10 植物在生育力和活力方面遭受了严重的近交衰退，显示少量成熟的花和极其缓慢的生长。尽管无性技术如花药培养然后染色体加倍可以产生完全纯合的二倍体马铃薯，但所有先前衍生的植物都是雄性不育的。相比之下，使用 Sli 的连续自交清除了所有致命的等位基因并选择了自育，从而产生了高度纯合的二倍体马铃薯，在长日照下保持雄性和雌性生育力和块茎化能力。