Abstract
Anthocyanins are responsible for the red pigmentation in the peel of apple (Malus × domestica Borkh.) fruit. Relatively few studies have investigated anthocyanins at the posttranscriptional level. MicroRNAs play an important role in plant growth and development by regulating gene expression at the posttranscriptional level. In this study, mdm-miR828 showed a relatively low expression level during the rapid fruit coloration period. However, the mdm-miR828 expression level increased in the late fruit coloration stage. Overexpression of mdm-miR828 inhibited anthocyanin synthesis in apple and Arabidopsis. Dual-luciferase and yeast one-hybrid assays showed that MdMYB1 is capable of binding to the promoter of mdm-MIR828b to promote its expression. The results indicate that mdm-miR828 is involved in a feedback regulatory mechanism associated with anthocyanin accumulation in apple. In addition, mdm-miR828 is involved in the inhibition of anthocyanin accumulation in response to high temperature.
Highlights
Apple (Malus × domestica Borkh.) is an economically important fruit crop that is cultivated worldwide
The mechanism of anthocyanin synthesis has been elucidated in many plant species, for example, petunia (Petunia hybrida; de Vetten et al, 1997; Quattrocchio et al, 1999; Spelt et al, 2000; Albert et al, 2011, 2014), Arabidopsis thaliana (Borevitz et al, 2000; Gonzalez et al, 2008; Petroni and Tonelli, 2011), grape (Vitis vinifera; Kobayashi et al, 2004; Hichri et al, 2010; Matus et al, 2010), nectarine (Prunus persica; Ravaglia et al, 2013), and strawberry (Fragaria × ananassa; Aharoni et al, 2001; Lin-Wang et al, 2010; Medina-Puche et al, 2014)
Anthocyanins are an important subclass of flavonoids that provide rich pigmentation to flowers and fruits, and have anticancer, antioxidation, antiaging, and other beneficial properties for human health (Venancio et al, 2017)
Summary
Apple (Malus × domestica Borkh.) is an economically important fruit crop that is cultivated worldwide. Many enzymes participate in this pathway, such as chalcone mdm-miR828 Regulate Anthocyanin Accumulation synthase (CHS), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), and flavonoid 3-O-glycosyltransferase (UFGT; Holton and Cornish, 1995; Shirley et al, 1995; Kim et al, 2003). These enzymes are coregulated by the MYB-bHLH-WD40 (MBW) transcription factor complex (Goff et al, 1992; Baudry et al, 2004; Lloyd et al, 2017). A cold-induced bHLH transcription factor, MdbHLH3, directly binds to the promoter of the structural gene MdUFGT and that of MdDFR to activate their expression and binds to the promoter of the regulatory gene MdMYB1 to promote its expression (Xie et al, 2012)
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