Germline fate determination is a critical event in sexual reproduction. Unlike animals, plants specify the germline by reprogramming somatic cells at the late stages of their development. However, the genetic basis of germline fate determination and how it evolved during the land plant evolution are still poorly understood. Here, we report that the plant homeodomain finger protein GERMLINE IDENTITY DETERMINANT (GLID) is a key regulator of the germline specification in liverwort, Marchantia polymorpha. Loss of the MpGLID function causes failure of germline initiation, leading to the absence of sperm and egg cells. Remarkably, the overexpression of MpGLID in M. polymorpha induces the ectopic formation of cells with male germline cell features exclusively in male thalli. We further show that MpBONOBO (BNB), with an evolutionarily conserved function, can induce the formation of male germ cell-like cells through the activation of MpGLID by directly binding to its promoter. The Arabidopsis (Arabidopsis thaliana) MpGLID ortholog, MALE STERILITY1 (AtMS1), fails to replace the germline specification function of MpGLID in M. polymorpha, demonstrating that a derived function of MpGLID orthologs has been restricted to tapetum development in flowering plants. Collectively, our findings suggest the presence of the BNB–GLID module in complex ancestral land plants that has been retained in bryophytes, but rewired in flowering plants for male germline fate determination.

中文翻译：

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BNB-GLID 模块调节 Marchantia polymorpha 的种系命运决定


种系命运决定是有性生殖中的关键事件。与动物不同，植物通过在发育的后期对体细胞进行重编程来指定种系。然而，确定种系命运的遗传基础及其在陆地植物进化过程中的进化方式仍然知之甚少。在这里，我们报道了植物同源域指蛋白 GERMLINE IDENTITY DETERMINANT （GLID） 是地钱 Marchantia polymorpha 种系规格的关键调节因子。MpGLID 功能的丧失导致种系起始失败，导致精子和卵细胞缺失。值得注意的是，MpGLID 在 M. polymorpha 中的过表达仅在雄性菌体中诱导具有雄性种系细胞特征的细胞的异位形成。我们进一步表明，MpBONOBO （BNB） 具有进化上保守的功能，可以通过直接结合其启动子来激活 MpGLID 诱导雄性生殖细胞样细胞的形成。拟南芥 （Arabidopsis thaliana） MpGLID 直系同源物，MALE STERILITY1 （AtMS1） 未能取代 M. polymorpha 中 MpGLID 的种系规格功能，表明 MpGLID 直系同源物的衍生功能仅限于开花植物的绒毡层发育。总的来说，我们的研究结果表明，BNB-GLID 模块存在于复杂的祖先陆地植物中，该模块保留在苔藓植物中，但在开花植物中重新连接以决定雄性种系命运。