Sexual differentiation is a fundamental process in the life cycles of land plants, ensuring successful sexual reproduction and thereby contributing to species diversity and survival. In the dioicous liverwort Marchantia polymorpha, this process is governed by an autosomal sex-differentiation locus comprising FGMYB, a female-promoting gene, and SUF, an antisense strand-encoded long non-coding RNA (lncRNA). SUF is specifically transcribed in male plants, and suppresses the expression of FGMYB, leading to male differentiation. However, the molecular mechanisms underlying this process remain elusive. Here, we show that SUF acts through its transcription to suppress FGMYB expression. Transgene complementation analysis using CRISPR/Cas9D1°A-based large-deletion mutants identified a genomic region sufficient for the sex differentiation switch function in the FGMYB-SUF locus. Inserting a transcriptional terminator sequence into the SUF-transcribed region resulted in the loss of SUF function and allowed expression of FGMYB in genetically male plants, leading to conversion of the sex phenotype from male to female. Partial deletions of SUF had no obvious impact on its function. Replacement of the FGMYB sequence with that of an unrelated gene did not affect the ability of SUF transcription to suppress sense-strand expression. Taken together, our findings suggest that the process of SUF transcription, rather than the resulting transcripts, is required for controlling sex differentiation in M. polymorpha.

中文翻译：

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反义长非编码 RNA（女​​性化抑制因子）的转录抑制地钱中雌性促进基因 FEMALE GMETOPHYTE MYB 的表达

性别分化是陆地植物生命周期的一个基本过程，确保成功的有性繁殖，从而促进物种多样性和生存。在雌雄异株地钱地钱中，这一过程由常染色体性别分化基因座控制，该基因座包含 FGMYB（一种雌性促进基因）和 SUF（一种反义链编码的长非编码 RNA (lncRNA)）。SUF在雄性植物中特异性转录，并抑制FGMYB的表达，导致雄性分化。然而，这一过程背后的分子机制仍然难以捉摸。在这里，我们证明 SUF 通过其转录来抑制 FGMYB 表达。使用基于 CRISPR/Cas9D1°A 的大缺失突变体进行转基因互补分析，确定了 FGMYB-SUF 基因座中足以实现性别分化转换功能的基因组区域。将转录终止子序列插入 SUF 转录区域会导致 SUF 功能丧失，并允许 FGMYB 在遗传雄性植物中表达，从而导致性别表型从雄性转变为雌性。SUF的部分缺失对其功能没有明显影响。用不相关基因的序列替换 FGMYB 序列并不影响 SUF 转录抑制有义链表达的能力。综上所述，我们的研究结果表明，控制多形性的性别分化需要 SUF 转录过程，而不是最终的转录本。