Ethanol application enhances freezing stress tolerance in Arabidopsis and sugar beet.

Abstract

Cold stress, especially freezing stress, is an important environmental factor that induces physiological damage in plants. In previous studies, we showed that ethanol application increases tolerance to high salinity, heat, high-intensity light, and drought, although the core mechanisms remain unclear. In this study, we investigated whether ethanol application could enhance freezing stress tolerance in Arabidopsis and sugar beet. Arabidopsis seedlings grown on agar plates were pretreated with 20 mM ethanol solution and then subjected to freezing. The survival ratio and growth indicators, including green leaf area, were higher in ethanol-pretreated seedlings than in water-pretreated seedlings. Similarly, in Arabidopsis seedlings grown in pots containing soil, 20 mM ethanol pretreatment increased the green leaf area after freezing treatment. Pretreatment with 80 mM ethanol solution of potted sugar beet seedlings grown in soil before exposure to freezing increased the survival ratio compared with that of water-pretreated seedlings. Transcriptome analysis using potted Arabidopsis plants grown in soil identified differentially expressed genes (DEGs), which included stress-related genes (LEA, DREB1A and ERF6) and anthocyanin biosynthesis-related genes (LDOX/ANS and DFR). Gene ontology analysis showed that DEGs associated with hypoxic response including oxidative stress response and anthocyanin-containing compound metabolic process were enriched in seedlings pretreated with 20 mM ethanol. Collectively, the results reveal that ethanol application effectively increases freezing stress tolerance and provide novel insights into the molecular mechanisms that underlie ethanol-mediated abiotic stress tolerance.