Multifaceted Roles of Plant Autophagy in Lipid and Energy Metabolism

Together with sugars and proteins, lipids constitute the main carbon reserves in plants. Lipids are selectively recycled and catabolized for energy production during development and in response to environmental stresses. Autophagy is a major catabolic pathway, operating in the recycling of cellular components in eukaryotes. Although the autophagic degradation of lipids has been mainly characterized in mammals and yeast, growing evidence has highlighted the role of autophagy in several aspects of lipid metabolism in plants. Here, we summarize recent findings focusing on autophagy functions in lipid droplet (LD) metabolism. We further provide novel insights regarding the relevance of autophagy in the maintenance and clearance of mitochondria and peroxisomes and its consequences for proper lipid usage and energy homeostasis in plants. Our understanding of autophagy function in lipid degradation in plants is understudied compared with the elucidated mechanisms in animals and yeast. However, the potential roles of plant autophagy in lipid recycling and metabolism are beginning to come to light.Macroautophagy is a versatile mechanism involved in lipid metabolism, operating both in the turnover of membrane components and in various aspects of reproduction, like pollen and seed metabolism.A mechanism resembling yeast microlipophagy was recently proposed in plant cells and is specifically active under starvation.The interplay between microlipophagy and lipolysis in plants seems to drive the efficient usage of lipid reserves.The autophagic maintenance of mitochondria and peroxisomes is essential for the optimal operation of these organelles, further enabling proper lipid turnover.