The Arabidopsis LSH1 and Oryza G1 (ALOG) protein is a family of plant-specific transcription factors that regulate reproductive growth in angiosperms. Despite their importance in plant development, little research has been conducted on ALOG proteins in basal land plants and the processes involved in their evolution remain largely unknown. Here, we studied the molecular evolution of ALOG family proteins. We found that ALOG proteins are absent in green algae but exist in all land plants analyzed as well as in some Charophycean algae, closest relatives of land plants. Multiple sequence alignments identified the high sequence conservation of ALOG domains in divergent plant lineages. Phylogenetic analyses also identified a distinct clade of ALOG protein member of lycophytes and bryophytes, including two of Marchantia polymorpha LATERAL ORGAN SUPPRESOR (MpLOS1 and MpLOS2) with a long branch length in MpLOS2. Consistent with this, the function of MpLOS1 was replaceable by Phycomitrella patens ALOG proteins, whereas MpLOS2 failed to replace the molecular function of MpLOS1. Moreover, the rice ALOG proteins, OsTAW1 and OsG1, were not able to replace the molecular function of MpLOS1 although we previously found that the function of OsG1 was replaceable by MpLOS1. Altogether, these findings suggest that ALOG proteins emerged before the evolution of land plants and that they exhibit functional conservation and diversification during the evolution of land plants. The finding that MpLOS1 is able to complement rice ALOG mutants but not vice versa also suggest the existence of conserved and the partly divergent functions of ALOG proteins in bryophytes and angiosperms.

中文翻译：

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陆地植物中植物特异性转录因子家族成员ALOG蛋白的起源和进化。

拟南芥LSH1和Oryza G1（ALOG）蛋白是一类植物特异性转录因子，可调节被子植物的生殖生长。尽管它们在植物发育中很重要，但在基础陆生植物中对ALOG蛋白的研究很少，并且其进化过程还不清楚。在这里，我们研究了ALOG家族蛋白的分子进化。我们发现绿藻中不存在ALOG蛋白，但存在于所有分析的陆地植物以及一些陆生植物的近亲Charophycean藻中。多个序列比对鉴定了不同植物谱系中ALOG结构域的高序列保守性。系统发育分析还确定了苔藓植物和苔藓植物的ALOG蛋白成员的独特分支，包括两个Marchantia polymorpha横向器官支持者（MpLOS1和MpLOS2），在MpLOS2中具有长的分支长度。与此相一致，MpLOS1的功能可以被枯草芽孢杆菌ALOG蛋白替代，而MpLOS2不能替代MpLOS1的分子功能。此外，水稻ALOG蛋白OsTAW1和OsG1不能替代MpLOS1的分子功能，尽管我们先前发现OsG1的功能可以被MpLOS1替代。总而言之，这些发现表明ALOG蛋白在陆地植物的进化之前就已经出现，并且它们在陆地植物的进化过程中表现出功能的保守性和多样性。