Molecular Mechanisms of Autophagy Regulation in Plants and Their Applications in Agriculture

Abstract

Autophagy is a highly conserved cellular process for the degradation and recycling of unnecessary cytoplasmic components in eukaryotes. Various studies have shown that autophagy plays a crucial role in plant growth, productivity, and survival. The extensive functions of plant autophagy have been revealed in numerous frontier studies, particularly those regarding growth adjustment, stress tolerance, the identification of related genes, and the involvement of metabolic pathways. However, elucidation of the molecular regulation of plant autophagy, particularly the upstream signaling elements, is still lagging. In this review, we summarize recent progress in research on the molecular mechanisms of autophagy regulation, including the roles of protein kinases, phytohormones, second messengers, and transcriptional and epigenetic control, as well as the relationship between autophagy and the 26S proteasome in model plants and crop species. We also discuss future research directions for the potential application of autophagy in agriculture.

HsfA1a confers pollen thermotolerance through upregulating antioxidant capacity, protein repair, and degradation in Solanum lycopersicum L.

“…In addition to protein repair, protein degradation mechanisms are actively involved in plant responses to abiotic stresses. The ubiquitin–proteasome system (UPS) and autophagy are two critical pathways for protein degradation [ 18 – 20 ]. The UPS utilizes the protease activity of the 26S proteasome to degrade target proteins, which are ubiquitinated by ubiquitin-activating enzyme (E1), ubiquitin-conjugating enzyme (E2), and the ubiquitin–protein ligase (E3) (E1–E2–E3) conjugated cascade [ 21 ].…”

From Soil Amendments to Controlling Autophagy: Supporting Plant Metabolism under Conditions of Water Shortage and Salinity

“…Observed effects of signaling events are interpreted with the assumption of a permanent autophagy potential, but the actual activity is downregulated by inhibitors, such as TOR and COST1 [285,287,288]. During environmental stress, autophagy can be activated by multiple mechanisms, including inactivation of the inhibitors [282,284,285,[289][290][291]. These regulatory events are fine-tuned by a signaling network, including the upregulation of gene expression of several transcription factors [284,292,293].…”

“…These regulatory events are fine-tuned by a signaling network, including the upregulation of gene expression of several transcription factors [284,292,293]. Signal transduction includes post-translational protein modification, such as protein phosphorylation and de-phosphorylation [285,291,294].…”

“…To date, the available information makes autophagy a promising candidate for research projects that are aimed at improving crop stress resistance [291,294,295]. While molecular site directed mutation is possible at laboratory scale, the application of results in the field will possibly lack public acceptance in several countries.…”

Monitoring Autophagy in Rice With GFP-ATG8 Marker Lines

“…To combat starvation, biotic, and abiotic stresses while maintaining growth, plants have to efficiently remobilize and reallocate nutrients and clear up pathogens, damaged proteins, and even organelles. Among the degradation/remobilization pathways employed by plants, an intracellular trafficking pathway termed autophagy is particularly important, and the defects in autophagy strongly compromise biomass production and yield ( Li et al, 2015 ; Wada et al, 2015 ; Have et al, 2017 ; Avin-Wittenberg et al, 2018 ; Signorelli et al, 2019 ; Cao et al, 2020 ; McLoughlin et al, 2020 ; Su et al, 2020 ).…”