Stimulation of Abscisic Acid Biosynthesis by Ethylene with Suppressive Action of MiR396 in Postharvest Strawberry Fruits

Both abscisic acid (ABA) and ethylene play essential roles in the ripening process of strawberry fruit (Fragaria × ananassa Duch.). In this study, the crosstalk between ABA and ethylene involved in strawberry fruit ripening was investigated. The results showed that ethylene triggered a 1.30-fold increase in ABA levels by suppressing the expression of miR396. Meanwhile, the silencing of miR396 (STTM396 reporter) demonstrated that miR396 acts as a negative regulatory factor of ABA biosynthesis by repressing FaNCED2 expression. Additionally, dual-luciferase assays indicated a 0.56-fold suppression of FaNCED2 promoter activity by miR396. These findings reveal a novel regulatory mechanism in which ethylene promotes ABA biosynthesis through the suppression of miR396 expression in postharvest strawberry fruit.