Emerging Roles of the Selective Autophagy in Plant Immunity and Stress Tolerance

Abstract

Autophagy is a conserved recycling system required for cellular homeostasis. Identifications of diverse selective receptors/adaptors that recruit appropriate autophagic cargoes have revealed critical roles of selective autophagy in different biological processes in plants. In this review, we summarize the emerging roles of selective autophagy in both biotic and abiotic stress tolerance and highlight the new features of selective receptors/adaptors and their interactions with both the cargoes and Autophagy-related gene 8s (ATG8s). In addition, we review how the two major degradation systems, namely the ubiquitin–proteasome system (UPS) and selective autophagy, are coordinated to cope with stress in plants. We especially emphasize how plants develop the selective autophagy as a weapon to fight against pathogens and how adapted pathogens have evolved the strategies to counter and/or subvert the immunity mediated by selective autophagy.

Silencing Autophagy-Related Gene 2 (ATG2) Results in Accelerated Senescence and Enhanced Immunity in Soybean

“…Autophagy is a recycling process that is unique in eukaryotic organisms [1-3]. In plants, autophagy has multiple functions in development and stress adaptations [1][2][3][4]. In Arabidopsis, many atg mutants exhibit an accelerated senescence and autoimmune phenotypes under natural growth conditions because they lack functional autophagy [9,20,28,33,35,59].…”

“…Autophagy involves the engulfing of cytoplasmic components in the autophagosomes, which subsequently fuse with the lysosomes (in animals) or vacuoles (in yeast and plants) and result in degradation of their cargoes by various hydrolases [1][2][3][4]. Cargo breakdown results in the production of molecular building blocks, such as amino acids, which are then released back into the cytoplasm for reuse [1][2][3].…”

“…Cargo breakdown results in the production of molecular building blocks, such as amino acids, which are then released back into the cytoplasm for reuse [1][2][3]. Autophagy could be non-selective or selective [1][2][3][4]. Non-selective autophagy, also referred to as bulk autophagy, uptakes and degrades the cytosolic compounds non-selectively in response to nutrient starvation, whereas selective autophagy mediates the degradation of target compounds by specific cargo receptors, which specifically interact with autophagosome membrane-anchored ubiquitin-like ATG8 proteins [5] via an ATG8-interacting motif (AIM) with a core W/Y/F-XX-L/I/V sequence [6][7][8].…”

Clearance or Hijack: Universal Interplay Mechanisms Between Viruses and Host Autophagy From Plants to Animals

“…Autophagy was initially thought to be a bulk catabolic process involving the re-mobilization of nutrients and the support of energy requirements, with cellular components being indiscriminately phagocytosed into the autophagosome. However, there is substantial evidence to indicate that autophagy can also degrade cytoplasmic cargo, such as misfolded/aggregated proteins, damaged organelles, and invading microorganisms, in a highly selective manner ( Gatica et al., 2018 ; Marshall and Vierstra, 2018 ; Ran et al., 2020 ). ATG8/LC3 plays a key role in selective autophagy.…”

Cargo Recognition and Function of Selective Autophagy Receptors in Plants

“…Characterization of these plant autophagy receptors and their cargos have provided important new insights into the critical roles of autophagy in plant responses to a broad spectrum of biotic and abiotic stresses. Several recent reviews have covered selective autophagy in plants that also include discussion on well-studied selective autophagy receptors from plants [34][35][36]. In this review, we provide a comprehensive discussion on selective autophagy receptors from Arabidopsis and other plants including several that have just been recently reported.…”