Table_2_Comprehensive analysis of peptide-coding genes and initial characterization of an LRR-only microprotein in Marchantia polymorpha.xlsx

In the past two decades, many plant peptides have been found to play crucial roles in various biological events by mediating cell-to-cell communications. However, a large number of small open reading frames (sORFs) or short genes capable of encoding peptides remain uncharacterized. In this study, we examined several candidate genes for peptides conserved between two model plants: Arabidopsis thaliana and Marchantia polymorpha. We examined their expression pattern in M. polymorpha and subcellular localization using a transient assay with Nicotiana benthamiana. We found that one candidate, MpSGF10B, was expressed in meristems, gemma cups, and male reproductive organs called antheridiophores. MpSGF10B has an N-terminal signal peptide followed by two leucine-rich repeat (LRR) domains and was secreted to the extracellular region in N. benthamiana and M. polymorpha. Compared with the wild type, two independent Mpsgf10b mutants had a slightly increased number of antheridiophores. It was revealed in gene ontology enrichment analysis that MpSGF10B was significantly co-expressed with genes related to cell cycle and development. These results suggest that MpSGF10B may be involved in the reproductive development of M. polymorpha. Our research should shed light on the unknown role of LRR-only proteins in land plants.

近二十年来，诸多植物肽类通过介导细胞间通讯，在多种生物学事件中发挥关键调控作用。然而，大量可编码肽类的小型开放阅读框（small open reading frames, sORFs）及短基因仍未被功能表征。本研究针对两种模式植物——拟南芥（Arabidopsis thaliana）与地钱（Marchantia polymorpha）间保守的肽类候选基因展开分析。我们借助本氏烟（Nicotiana benthamiana）瞬时表达体系，检测了这些候选基因在地钱中的表达模式与亚细胞定位情况。研究发现，候选基因MpSGF10B在分生组织、胞芽杯以及雄性生殖结构雄器托（antheridiophores）中均有表达。MpSGF10B带有N端信号肽，其后包含两个亮氨酸富集重复（leucine-rich repeat, LRR）结构域，且在本氏烟与地钱中均可被分泌至胞外区域。与野生型相比，两株独立的Mpsgf10b突变体的雄器托数量略有提升。通过基因本体（Gene Ontology, GO）富集分析发现，MpSGF10B与细胞周期及发育相关基因存在显著共表达关系。上述结果表明，MpSGF10B可能参与地钱的生殖发育过程。本研究可为阐明陆生植物中仅含LRR结构域蛋白的未知功能提供新的研究视角。