Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.
J Plant Res. 2020 May;133(3):323-329. doi: 10.1007/s10265-020-01171-6. Epub 2020 Feb 12.
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.
拟南芥 LSH1 和水稻 G1（ALOG）蛋白是一类植物特异性转录因子，它们在被子植物的生殖生长中起调节作用。尽管它们在植物发育中很重要，但对基生植物中的 ALOG 蛋白的研究甚少，其进化过程的大部分仍不清楚。在这里，我们研究了 ALOG 家族蛋白的分子进化。我们发现 ALOG 蛋白在绿藻中不存在，但存在于所有分析的陆生植物以及一些最接近陆生植物的Charophycean 藻类中。多重序列比对确定了 ALOG 结构域在不同植物谱系中的高度序列保守性。系统发育分析还鉴定了一个独特的石松类和苔藓类 ALOG 蛋白分支，包括两个 Marchantia polymorpha LATERAL ORGAN SUPPRESOR（MpLOS1 和 MpLOS2），它们在 MpLOS2 中具有较长的分支长度。与此一致的是，MpLOS1 的功能可被 Phycomitrella patens ALOG 蛋白取代，而 MpLOS2 未能取代 MpLOS1 的分子功能。此外，尽管我们之前发现 OsG1 的功能可被 MpLOS1 取代，但水稻 ALOG 蛋白 OsTAW1 和 OsG1 无法取代 MpLOS1 的分子功能。总之，这些发现表明 ALOG 蛋白在陆生植物进化之前就已经出现，并且在陆生植物的进化过程中表现出功能保守和多样化。MpLOS1 能够补充水稻 ALOG 突变体但反之则不能的发现也表明 ALOG 蛋白在苔藓植物和被子植物中具有保守和部分不同的功能。
