National Engineering Laboratory for Endangered Medicinal Resource Development in Northwest China, Key Laboratory of Medicinal Resources and Natural Pharmaceutical Chemistry of Ministry of Education, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China.
International Research Organization for Advanced Science and Technology (IROAST), Kumamoto University, Kumamoto, 860-8555, Japan.
New Phytol. 2022 Sep;235(6):2300-2312. doi: 10.1111/nph.18291. Epub 2022 Jun 20.
Known for their regulatory roles in stem cell homeostasis, CLAVATA3/ESR-RELATED (CLE) peptides also function as mediators of external stimuli such as hormones. De novo shoot regeneration, representing the remarkable plant cellular plasticity, involves reconstitution of stem cells under control of stem-cell regulators. Yet whether and how stem cell-regulating CLE peptides are implicated in plant regeneration remains unknown. By CRISPR/Cas9-induced loss-of-function studies, peptide application, precursor overexpression, and expression analyses, the role of CLE1-CLE7 peptides and their receptors in de novo shoot regeneration was studied in Arabidopsis thaliana. CLE1-CLE7 are induced by callus-induction medium and dynamically expressed in pluripotent callus. Exogenously-applied CLE1-CLE7 peptides or precursor overexpression effectively leads to shoot regeneration suppression, whereas their simultaneous mutation results in enhanced regenerative capacity, demonstrating that CLE1-CLE7 peptides redundantly function as negative regulators of de novo shoot regeneration. CLE1-CLE7-mediated shoot regeneration suppression is impaired in loss-of-function mutants of callus-expressed CLAVATA1 (CLV1) and BARELY ANY MERISTEM1 (BAM1) genes, indicating that CLV1/BAM1 are required for CLE1-CLE7-mediated shoot regeneration signaling. CLE1-CLE7 signaling resulted in transcriptional repression of WUSCHEL (WUS), a stem cell-promoting transcription factor known as a principal regulator of plant regeneration. Our results indicate that functionally-redundant CLE1-CLE7 peptides genetically act through CLV1/BAM1 receptors and repress WUS expression to modulate shoot-regeneration capacity, establishing the mechanistic basis for CLE1-CLE7-mediated shoot regeneration and a novel role for CLE peptides in hormone-dependent developmental plasticity.
已知 CLAVATA3/ESR-RELATED（CLE）肽在干细胞稳态中具有调节作用，它们还作为外部刺激（如激素）的介质发挥作用。从头再生新梢，代表着植物细胞显著的可塑性，涉及在干细胞调节剂控制下重新构成干细胞。然而，调节干细胞的 CLE 肽是否以及如何参与植物再生仍然未知。通过 CRISPR/Cas9 诱导的功能丧失研究、肽应用、前体过表达和表达分析，研究了 CLE1-CLE7 肽及其受体在拟南芥从头再生中的作用。CLE1-CLE7 被愈伤组织诱导培养基诱导，并在多能愈伤组织中动态表达。外源性应用 CLE1-CLE7 肽或前体过表达有效抑制芽再生，而它们的同时突变导致再生能力增强，表明 CLE1-CLE7 肽作为从头再生新梢的负调节剂冗余地发挥作用。CLE1-CLE7 介导的芽再生抑制在愈伤组织表达的 CLAVATA1（CLV1）和 BARELY ANY MERISTEM1（BAM1）基因功能丧失突变体中受损，表明 CLV1/BAM1 是 CLE1-CLE7 介导的芽再生信号所必需的。CLE1-CLE7 信号导致 WUSCHEL（WUS）的转录抑制，WUS 是一种已知的干细胞促进转录因子，是植物再生的主要调节剂。我们的结果表明，功能冗余的 CLE1-CLE7 肽通过 CLV1/BAM1 受体遗传作用，并抑制 WUS 的表达来调节芽再生能力，为 CLE1-CLE7 介导的芽再生和 CLE 肽在激素依赖性发育可塑性中的新作用建立了机制基础。
