The miR156/SPL12 module orchestrates fruit colour change through directly regulating ethylene production pathway in blueberry

Abstract

SummaryColour change is an important event during fruit ripening in blueberry. It is well known that miR156/SPLs act as regulatory modules mediating anthocyanin biosynthesis and ethylene plays critical roles during colour change, but the intrinsic connections between the two pathways remain poorly understood. Previously, we demonstrated that blueberry VcMIR156a/VcSPL12 affects the accumulation of anthocyanins and chlorophylls in tomato and Arabidopsis. In this study, we first showed that VcMIR156a overexpression in blueberry led to enhanced anthocyanin biosynthesis, decreased chlorophyll accumulation, and, intriguingly, concomitant elevation in the expression of ethylene biosynthesis genes and the level of the ethylene precursor ACC. Conversely, VcSPL12 enhanced chlorophyll accumulation and suppressed anthocyanin biosynthesis and ACC synthesis in fruits. Moreover, the treatment with ethylene substitutes and inhibitors attenuated the effects of VcMIR156a and VcSPL12 on pigment accumulation. Protein‐DNA interaction assays indicated that VcSPL12 could specifically bind to the promoters and inhibit the activities of the ethylene biosynthetic genes VcACS1 and VcACO6. Collectively, our results show that VcMIR156a/VcSPL12 alters ethylene production through targeting VcACS1 and VcACO6, therefore governing fruit colour change. Additionally, VcSPL12 may directly interact with the promoter region of the chlorophyll biosynthetic gene VcDVR, thereby activating its expression. These findings established an intrinsic connection between the miR156/SPL regulatory module and ethylene pathway.

The Ethylene Biosynthetic Enzymes, 1-Aminocyclopropane-1-Carboxylate (ACC) Synthase (ACS) and ACC Oxidase (ACO): The Less Explored Players in Abiotic Stress Tolerance

“…A study showed that in Arabidopsis, miR3933 post-transcriptionally cleaved the ACO5; similarly, in rice, miR5809 and miR531a/b regulate ACO post-transcriptionally [50]. VcMIR156a/VcSPL12 influences fruit color change in blueberries by regulating ethylene production through the targeting of VcACS1 and VcACO6, demonstrating a crucial connection between the miR156/SPL regulatory module and the ethylene pathway [105].…”

The ncRNAs Involved in the Regulation of Abiotic Stress-Induced Anthocyanin Biosynthesis in Plants

“…Furthermore, in blueberry fruit coloration, the VcMIR156a-VcSPL12 module regulates the anthocyanin accumulation by directly regulating the ethylene production path-way [121,122]. Ethylene has been reported to be a key regulator of salinity stress tolerance in plants via maintaining the homeostasis of Na + /K + , nutrients, reactive oxygen species (ROS), and cross-talk of ethylene signaling with other phytohormones [123].…”