Department of Biology, University of Iowa, 129 E. Jefferson St., Iowa City, IA 52242, USA.
The Translational Genomics Research Institute, 445 N. Fifth St., Phoenix, AZ 85004, USA.
Plant Sci. 2023 Oct;335:111812. doi: 10.1016/j.plantsci.2023.111812. Epub 2023 Jul 31.
Land plant sexual reproduction involves the transition of cells from somatic to reproductive identity during post-embryonic development. In Arabidopsis, the leucine-rich repeat receptor-like kinase EXCESS MICROSPOROCYTES1 (EXS/EMS1) restricts the number of sporogenous cells during the transition from diploid tissue to haploid spore production by promoting the formation of the tapetum cell layer within the anther. Although all land plants studied contain EMS1 genes, its function is unknown beyond a few angiosperms. In the model fern Ceratopteris (Ceratopteris richardii), we discovered an EMS1 homolog (CrEMS1) that functions to suppress formation of reproductive structures on vegetative leaves of the fern sporophyte, a role not found in angiosperms. Suppression of CrEMS1 by RNAi did not affect sporogenesis on reproductive leaves but did affect antheridium production of the fern gametophyte. Expression patterns of CrEMS1 across developmental stages suggest threshold levels of CrEMS1 control the specification of reproductive organs during both generations of the fern. Additional EMS1 homologs present in the fern genome suggest a dynamic role of EMS1 receptors in the evolution of reproductive development in vascular plants.
陆地植物的有性生殖涉及到细胞从体细胞到生殖体的身份转变，这一过程发生在胚胎后发育时期。在拟南芥中，富含亮氨酸重复的受体样激酶 EXCESS MICROSPOROCYTES1（EXS/EMS1）通过促进花药中绒毡层细胞层的形成，限制了从二倍体组织向单倍体孢子产生的过程中转变成孢子发生细胞的数量。尽管所有研究过的陆地植物都含有 EMS1 基因，但除了少数被子植物外，其功能尚不清楚。在模式蕨类植物（凤尾蕨 Ceratopteris richardii）中，我们发现了一个 EMS1 同源物（CrEMS1），它的功能是抑制蕨类植物孢子体营养叶上生殖结构的形成，而在被子植物中没有发现这一功能。通过 RNAi 抑制 CrEMS1 的表达不会影响生殖叶的孢子发生，但会影响蕨类植物配子体的精子囊的产生。CrEMS1 在不同发育阶段的表达模式表明，CrEMS1 的阈值水平控制着蕨类植物两代生殖器官的特化。蕨类植物基因组中存在的其他 EMS1 同源物表明，EMS1 受体在维管植物生殖发育的进化中具有动态作用。
