College of Life Sciences, Nanjing Normal University, Nanjing, 210023, China.
Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, 518055, Shenzhen, China.
Commun Biol. 2023 Apr 26;6(1):460. doi: 10.1038/s42003-023-04849-4.
Apical hooks are functional innovations only observed in angiosperms, which effectively protect the apical meristems out of damage during plant seedlings penetrating soil covers. Acetyltransferase like protein HOOKLESS1 (HLS1) in Arabidopsis thaliana is required for hook formation. However, the origin and evolution of HLS1 in plants are still not solved. Here, we traced the evolution of HLS1 and found that HLS1 originated in embryophytes. Moreover, we found that Arabidopsis HLS1 delayed plant flowering time, in addition to their well-known functions in apical hook development and newly reported roles in thermomorphogenesis. We further revealed that HLS1 interacted with transcription factor CO and repressed the expression of FT to delay flowering. Lastly, we compared the functional divergence of HLS1 among eudicot (A. thaliana), bryophytes (Physcomitrium patens and Marchantia polymorpha) and lycophyte (Selaginella moellendorffii). Although HLS1 from these bryophytes and lycophyte partially rescued the thermomorphogenesis defects in hls1-1 mutants, the apical hook defects and early flowering phenotypes could not be reversed by either P. patens, M. polymorpha or S. moellendorffii orthologs. These results illustrate that HLS1 proteins from bryophytes or lycophyte are able to modulate thermomorphogenesis phenotypes in A. thaliana likely through a conserved gene regulatory network. Our findings shed new light on the understanding of the functional diversity and origin of HLS1, which controls the most attractive innovations in angiosperms.
顶端弯钩是仅在被子植物中观察到的功能创新，它有效地保护了顶端分生组织免受植物幼苗穿透土壤覆盖物时的损伤。拟南芥中的乙酰转移酶样蛋白 HOOKLESS1（HLS1）是弯钩形成所必需的。然而，HLS1 在植物中的起源和进化仍未解决。在这里，我们追踪了 HLS1 的进化，发现 HLS1 起源于胚胎植物。此外，我们发现拟南芥 HLS1 除了在顶端弯钩发育和新报道的热形态发生中的作用外，还延迟了植物的开花时间。我们进一步揭示 HLS1 与转录因子 CO 相互作用，抑制 FT 的表达以延迟开花。最后，我们比较了拟南芥（A. thaliana）、苔藓植物（Physcomitrium patens 和 Marchantia polymorpha）和石松植物（Selaginella moellendorffii）中 HLS1 的功能分化。尽管这些苔藓植物和石松植物的 HLS1 部分挽救了 hls1-1 突变体的热形态发生缺陷，但 P. patens、M. polymorpha 或 S. moellendorffii 同源物均不能逆转顶端弯钩缺陷和早花表型。这些结果表明，来自苔藓植物或石松植物的 HLS1 蛋白能够通过保守的基因调控网络来调节拟南芥的热形态发生表型。我们的发现为理解 HLS1 的功能多样性和起源提供了新的视角，HLS1 控制着被子植物中最具吸引力的创新。
