WUSCHEL-responsive At5g65480 interacts with CLAVATA components in vitro and in transient expression

ATG8-Interacting Motif: Evolution and Function in Selective Autophagy of Targeting Biological Processes

Autophagy is an evolutionarily conserved vacuolar process functioning in the degradation of cellular components for reuse. In plants, autophagy is generally activated upon stress and its regulation is executed by numbers of AuTophaGy-related genes (ATGs), of which the ATG8 plays a dual role in both biogenesis of autophagosomes and recruitment of ATG8-interacting motif (AIM) anchored selective autophagy receptors (SARs). Such motif is either termed as AIM or ubiquitin-interacting motif (UIM), corresponding to the LC3-interacting region (LIR)/AIM docking site (LDS) or the UIM docking site (UDS) of ATG8, respectively. To date, dozens of AIM or UIM containing SARs have been characterized. However, the knowledge of these motifs is still obscured. In this review, we intend to summarize the current understanding of SAR proteins and discuss the conservation and diversification of the AIMs/UIMs, expectantly providing new insights into the evolution of them in various biological processes in plants.

Real-time dynamics of peptide ligand-dependent receptor complex formation in planta

The CLAVATA (CLV) and flagellin (flg) signaling pathways act through peptide ligands and closely related plasma membrane-localized receptor-like kinases (RLKs). The plant peptide CLV3 regulates stem cell homeostasis, whereas the bacterial flg22 peptide elicits defense responses. We applied multiparameter fluorescence imaging spectroscopy (MFIS) to characterize the dynamics of RLK complexes in the presence of ligand in living plant cells expressing receptor proteins fused to fluorescent proteins. We found that the CLV and flg pathways represent two different principles of signal transduction: flg22 first triggered RLK heterodimerization and later assembly into larger complexes through homomerization. In contrast, CLV receptor complexes were preformed, and ligand binding stimulated their clustering. This different behavior likely reflects the nature of these signaling pathways. Pathogen-triggered flg signaling impedes plant growth and development; therefore, receptor complexes are formed only in the presence of ligand. In contrast, CLV3-dependent stem cell homeostasis continuously requires active signaling, and preformation of receptor complexes may facilitate this task.