The MdBBX22–miR858–MdMYB9/11/12 module regulates proanthocyanidin biosynthesis in apple peel

第一作者：Bo Zhang

第一单位：西北农林科技大学

通讯作者：Zheng-Yang Zhao

 Abstarct 

背景回顾：Proanthocyanidins (PAs) have antioxidant properties and are beneficial to human health. The fruit of apple (Malus × domestica Borkh.), especially the peel, are rich in various flavonoids, such as PAs, and thus are an important source of dietary antioxidants. Previous research on the regulation of PAs in apple has mainly focused on the transcription level, whereas studies conducted at the post-transcriptional level are relatively rare. 

原花色素（PAs）具有抗氧化特性，有益于人类健康。苹果的果实，尤其是果皮，富含PAs等各种类黄酮，因此是人类膳食抗氧化剂的重要来源。以往对苹果中PAs的调控研究主要集中在转录水平，而在转录后水平进行的研究相对较少。

主要研究：In this study, we investigated the function of mdm-miR858, a miRNA with multiple functions in plant development, in the peel of apple fruit. 

本文中，作者研究了mdm-miR858在苹果果皮中的功能，而mdm-miR858是一种在植物发育中具有多种功能的miRNA。

结果1-mdm-miR858-MdMYB9/11/12：We showed that mdm-miR858 negatively regulated PA accumulation by targeting MdMYB9/11/12 in the peel. During fruit development, mdm-miR858 expression was negatively correlated with MdMYB9/11/12 expression and PA accumulation. A 5′-RACE experiment, GUS staining assays, and transient luminescent assays indicated that mdm-miR858 cleaved and inhibited the expression of MdMYB9/11/12. Overexpression of mdm-miR858 in apple calli, tobacco, and Arabidopsis reduced the accumulation of PAs induced by overexpression of MdMYB9/11/12. 

作者发现，mdm-miR858通过靶向果皮中的MdMYB9/11/12，负调节PAs的积累。在果实发育过程中，mdm-miR858的表达与MdMYB9/11/12的表达以及PAs的积累呈负相关。5′-RACE、GUS染色以及瞬时荧光实验表明，mdm-miR858能够切割并抑制MdMYB9/11/12的表达。mdm-miR858在苹果愈伤组织、烟草和拟南芥中的过表达，均能够减少由MdMYB9/11/12过表达所诱导的PA积累。

结果2-MdBBX22-mdm-miR858-MdMYB9/11/12：Futhermore, we found that MdBBX22 bound to the mdm-miR858 promoter and induced its expression. Overexpression of MdBBX22 induced expression of mdm-miR858 to inhibit the accumulation of PAs in apple calli overexpressing MdMYB9/11/12. Under light stress, MdBBX22 induced mdm-miR858 expression to inhibit PA accumulation and thereby indirectly enhanced anthocyanin synthesis in the peel. 

此外，作者还发现MdBBX22能够结合到mdm-miR858的启动子上，诱导后者的表达。MdBBX22过表达会诱导mdm-miR858的表达，从而抑制MdMYB9/11/12过表达苹果愈伤中的PA积累。在光胁迫下，MdBBX22诱导的mdm-miR858表达抑制了PA的积累，从而间接增强了果皮中花色苷的合成。

结论：The present results revealed that the MdBBX22–miR858–MdMYB9/11/12 module regulates PA accumulation in apple. The findings provide a reference for further studies of the regulatory mechanism of PA accumulation and the relationship between PAs and anthocyanins.

目前的结果显示，MdBBX22–miR858–MdMYB9/11/12模块调节苹果中的PA积累。这些发现为进一步研究PA积累的调节机制以及PAs与花色苷之间的关系提供了参考。

** 赵政阳 **

doi: https://doi.org/10.1111/pbi.13839

Journal: Plant Biotechnology Journal

First Published: May 08, 2022