Autophagy deficiency confers freezing tolerance in Arabidopsis thaliana.

BACKGROUND: Plants have evolved multiple strategies to cope with the ever-changing external environment. Autophagy, as one of the crucial mechanisms involved, has been demonstrated to play a pivotal role in plant responses and adaptation to abiotic stresses. However, the precise molecular mechanisms underlying the role of autophagy in mediating cold stress remain to be fully elucidated. RESULTS: In this study, we demonstrated that autophagy mutants presented increased freezing tolerance under both non-acclimated and cold-acclimated conditions in Arabidopsis. Autophagy positively regulates the expression of anthocyanin biosynthesis-related genes, thereby influencing anthocyanin accumulation in Arabidopsis under low-temperature conditions. Moreover, we found that cold stress directly suppresses the expression of autophagy-related genes and reduces autophagic flux in Arabidopsis. The RNA-seq data revealed that cold-responsive genes were pre-activated in the autophagy mutant atg13ab even before cold treatment. Additionally, we observed constitutive accumulation of the dehydrin protein COR47 in atg13ab mutant. CONCLUSIONS: Taken together, these data suggest that autophagy is a negative regulator of freezing tolerance in Arabidopsis.