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Abstract In plants, autophagy is a conserved process by which intracellular materials, including damaged proteins, aggregates, and entire organelles, are trafficked to the vacuole for degradation, thus maintaining cellular homeostasis. The past few decades have seen extensive research into the core components of the central autophagy machinery and their physiological roles in plant growth and development as well as responses to biotic and abiotic stresses. Moreover, several methods have been established for monitoring autophagic activities in plants, and these have greatly facilitated plant autophagy research. However, some of the methodologies are prone to misuse or misinterpretation, sometimes casting doubt on the reliability of the conclusions being drawn about plant autophagy. Here, we summarize the methods that are widely used for monitoring plant autophagy at the physiological, microscopic, and biochemical levels, including discussions of their advantages and limitations, to provide a guide for studying this important process. 

The retromer is a heteromeric protein complex that localizes to endosomal membranes and drives the formation of endosomal tubules that recycle membrane protein cargoes. In plants, the retromer plays essential and canonical functions in regulating the transport of vacuolar storage proteins and the recycle of endocytosed plasma membrane proteins (PM); however, the mechanisms underlying the regulation of assembly, protein stability, and membrane recruitment of the plant retromer complex remain to be elucidated. In this study, we identify a plant-unique endosomal regulator termed BLISTER (BLI), which colocalizes and associates with the retromer complex by interacting with the retromer core subunits VPS35 and VPS29. Depletion of BLI perturbs the assembly and membrane recruitment of the retromer core VPS26-VPS35-VPS29 trimer. Consequently, depletion of BLI disrupts retromer-regulated endosomal trafficking function, including transport of soluble vacuolar proteins and recycling of endocytosed PIN-FORMED (PIN) proteins from the endosomes back to the PM. Moreover, genetic analysis in Arabidopsis thaliana mutants reveals BLI and core retromer interact genetically in the regulation of endosomal trafficking. Taken together, we identified BLI as a plant-specific endosomal regulator, which functions in retromer pathway to modulate the recycling of endocytosed PM proteins and the trafficking of soluble vacuolar cargoes. 

With growing populations and pressing environmental problems, future economies will be increasingly plant-based. Now is the time to reimagine plant science as a critical component of fundamental science, agriculture, environmental stewardship, energy, technology and healthcare. This effort requires a conceptual and technological framework to identify and map all cell types, and to comprehensively annotate the localization and organization of molecules at cellular and tissue levels. This framework, called the Plant Cell Atlas (PCA), will be critical for understanding and engineering plant development, physiology and environmental responses. A workshop was convened to discuss the purpose and utility of such an initiative, resulting in a roadmap that acknowledges the current knowledge gaps and technical challenges, and underscores how the PCA initiative can help to overcome them.