Amphicarpy (seed heteromorphy) is a unique and fascinating reproductive strategy wherein a single plant produces both aerial and subterranean fruits. This strategy is believed to be an adaptation to life under stressful or uncertain environments. Here, we sequenced and de novo assembled a chromosome-level genome assembly of the legume Amphicarpaea edgeworthii Benth. The 299-Mb A. edgeworthii genome encodes 27 899 protein-coding genes and is the most compact sequenced legume genome reported until date. Its reduced genome size may be attributed to the reduced long-terminal repeat retrotransposon content, which stems from the unequal homologous recombination. Gene families related to immunity and stress resistance have been contracted in A. edgeworthii, which is consistent with the notion that the amphicarpic reproductive strategy may be a complementary mechanism for its weak environmental-adaptation ability. We demonstrated the ‘ABCE’ model for the differentiation of chasmogamous and cleistogamous flowers. In addition, the characteristics of aerial and subterranean seeds in hard-seededness were explored. Thus, we suggest that the A. edgeworthii genome, which is the first of an amphicarpic plant, offers significant insights into its unusual reproductive strategy that is a key resource towards comprehending the evolution of angiosperms.

中文翻译：

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从豆科植物 Amphicarpaea edgeworthii 的紧凑基因组中洞察两性结实

Amphicarpy（种子异形）是一种独特而引人入胜的繁殖策略，其中一株植物同时产生地上和地下果实。这种策略被认为是对压力或不确定环境下的生活的适应。在这里，我们测序并从头组装豆科植物Amphicarpaea edgeworthii Benth的染色体水平基因组组装。299-Mb A. edgeworthii基因组编码 27 899 个蛋白质编码基因，是迄今为止报道的最紧凑的已测序豆科植物基因组。其减少的基因组大小可能归因于减少的长末端重复反转录转座子含量，这源于不平等的同源重组。与免疫和抗逆性相关的基因家族已在A. edgeworthii，这与两性生殖策略可能是其弱环境适应能力的补充机制的观点一致。我们展示了用于区分交配和闭锁花的“ABCE”模型。此外，还探讨了硬种子中空中和地下种子的特征。因此，我们建议A. edgeworthii基因组是第一个两性植物，它提供了对其不寻常的繁殖策略的重要见解，这是理解被子植物进化的关键资源。