Knockdown of Sly-miR160a using short tandem target mimic (STTM) enhanced expression of auxin signaling genes and delayed postharvest ripening of tomato fruit

Abstract

The miR160 is a highly conserved microRNA (miRNA) that regulates the auxin signaling pathway through negative regulation of auxin response factors (ARFs) and plays pivotal roles in fruit development. In the present study, the knockdown of miR160a using short tandem target mimic (STTM 160a) and overexpression of miR160a (miR160a-OE) transgenic tomato lines were generated to investigate the possible roles of miR160 in postharvest ripening tomato fruit. The results showed that the STTM 160a increased total chlorophyll content, reduced lycopene and total carotenoid accumulation, weight loss, and respiration rate while increasing firmness in tomato fruit compared with the wild-type (WT) and miR160a-OE. Additionally, miR160a-OE lines exhibited a typical auxin hypersensitivity and postharvest ripening acceleration, whereas STTM 160a lines displayed an auxin hyposensitivity and postharvest ripening reduction. Moreover, the relative expression levels of ARF10A (Solyc11g069500.2.1), ARF10B (Solyc06g075150.3.1), ARF17 (Solyc11g013480.2.1), and Aux/IAA genes were up-regulated in STTM 160a lines. The results suggest that the knockdown of Sly-miR160a delays postharvest ripening in tomato fruit, and provide valuable information for genetic engineering in controlling developmental processes.