Abstract

Color change is an important event during fruit maturation in blueberry, usually depending on chlorophyll degradation and anthocyanin accumulation. MicroRNA156 (miR156)–SPL modules are an important group of regulatory hubs involved in the regulation of anthocyanin biosynthesis. However, little is known regarding their roles in blueberry or in chlorophyll metabolism during color change. In this study, a MIR156 gene (VcMIR156a) was experimentally identified in blueberry (Vaccinium corymbosum). Overexpression of VcMIR156a in tomato (Solanum lycopersicum) enhanced anthocyanin biosynthesis and chlorophyll degradation in the stem by altering pigment-associated gene expression. Further investigation indicated that the VcSPL12 transcript could be targeted by miR156, and showed the reverse accumulation patterns during blueberry fruit development and maturation. Noticeably, VcSPL12 was highly expressed at green fruit stages, while VcMIR156a transcripts mainly accumulated at the white fruit stage when expression of VcSPL12 was dramatically decreased, implying that VcMIR156a–VcSPL12 is a key regulatory hub during fruit coloration. Moreover, VcSPL12 decreased the expression of several anthocyanin biosynthetic and regulatory genes, and a yeast two-hybrid assay indicated that VcSPL12 interacted with VcMYBPA1. Intriguingly, expression of VcSPL12 significantly enhanced chlorophyll accumulation and altered the expression of several chlorophyll-associated genes. Additionally, the chloroplast ultrastructure was altered by the expression of VcMIR156a and VcSPL12. These findings provide a novel insight into the functional roles of miR156–SPLs in plants, especially in blueberry fruit coloration.

中文翻译：

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蓝莓MIR156a / SPL12模块可协调果实成熟期间叶绿素和花色苷的积累。

摘要

颜色变化是蓝莓果实成熟期间的重要事件，通常取决于叶绿素的降解和花色苷的积累。MicroRNA156（miR156）– SPL模块是参与花色苷生物合成调控的重要调控枢纽。然而，关于它们在变色过程中在蓝莓或叶绿素代谢中的作用鲜为人知。在这项研究中，通过实验鉴定了蓝莓（Vaccinium corymbosum）中的MIR156基因（VcMIR156a）。的过表达VcMIR156a在番茄（番茄）通过改变色素相关基因的表达来增强茎中花色苷的生物合成和叶绿素降解。进一步的研究表明，VcSPL12转录本可被miR156靶向，并显示蓝莓果实发育和成熟过程中的反向积累模式。值得注意的是，VcSPL12在绿色水果阶段高表达，而VcMIR156a转录本主要在白色水果阶段积累，此时VcSPL12的表达急剧下降，这意味着VcMIR156a – VcSPL12是水果着色期间的关键调控中心。此外，VcSPL12降低了一些花色苷生物合成和调控基因的表达，并且酵母双杂交试验表明VcSPL12与VcMYBPA1相互作用。有趣的是，VcSPL12的表达显着增强了叶绿素的积累，并改变了一些与叶绿素相关的基因的表达。此外，叶绿体超微结构被VcMIR156a和VcSPL12的表达所改变。这些发现提供了一种新颖的洞察miR156-的功能角色声压级在植物中，特别是在蓝莓果实着色。