MiR858b Inhibits Proanthocyanidin Accumulation by the Repression of DkMYB19 and DkMYB20 in Persimmon

Abstract

Persimmon proanthocyanidin (PA) biosynthesis is controlled by structural genes and regulated by transcription factors (TFs). MicroRNAs are a key factor involved in regulating gene expression at the posttranscriptional level whose functions in persimmon PA biosynthesis are poorly understood. Here, we identified a microRNA, miR858b, that putatively targets two R2R3-MYB TFs, DkMYB19 and DkMYB20. DkMYB19, DkMYB20, and miR858b showed divergent expression patterns during fruit development, and the interaction between miR858b and DkMYB19 or DkMYB20 was experimentally validated by 5′ RNA ligase-mediated RACE, LUC enzyme activity analysis, and GFP signal detection. The DkMYB19 localized to the nucleus as well as the cytoplasm and DkMYB20 localized to the nucleus. The overexpression of miR858b led to the downregulation of DkMYB19 and DkMYB20, which reduced the content of PA, whereas a reduction in miR858b activity upregulated DkMYB19 and DkMYB20, resulting in a high content of PA in leaves transiently expressing a small tandem target mimic construct for blocking miR858 (STTM858b) in vivo. The transient transformation of miR858b in fruit discs in vitro also reduced the content of PA, while the content of PA increased under the transient transformation of fruit discs with STTM858b, DkMYB19, or DkMYB20. A similar phenomenon was observed upon the overexpression of miR858b in wild-type (WT) Arabidopsis and DkMYB19 or DkMYB20 in persimmon leaf calli. These findings suggested that miR858b repressed the expression of DkMYB19 and DkMYB20, which contributed to the PA accumulation in persimmon.

GhmiR858 Inhibits the Accumulation of Proanthocyanidins by Targeting GhTT2L in Cotton (Gossypium hirsutum)

“…In grapes, the activation of miR858 led to a significant downregulation of its target gene VvMYB114 , a repressor of anthocyanin, thereby inducing excessive anthocyanins accumulation . In contrast, the reduced expression of miR858 using the STTM strategy improved the accumulation of anthocyanin by targeting SlMYB48-like , MdMYB9 , and MdMYBPA1 transcripts in tomatoes and apple calli. , In addition, DkMYB20 was conducive to regulating the biosynthesis of PAs, whereas miR858b directly repressed the transcription of DkMYB20 , which contributed to the accurate regulation of PA accumulation in persimmons . In apple calli, miR858 induced the accumulation of PAs by downregulating the expression of the three transcription factors MdMYB9 , MdMYB11 , and MdMYB12 .…”

“…Phylogenetic tree analysis indicated that GhTT2L clustered into the PA-related MYB clade and was closer in systemic evolution to AtTT2, DkMYB2, and VvMYBPA2 (Figures 1B, S2, and Table S2), which were previously described as biosynthetic regulators of PAs. 6,10 Furthermore, GhTT2L-pGBKT7-positive yeast cells grew normally on yeast amino acid deficient medium, indicating that GhTT2L possessed transcriptional activation activities (Figure 1C). Interestingly, the expression pattern of GhTT2L was contrary to that of GhmiR858 and significantly decreased in HS2 (Figure 1D).…”

“…In Cucumis sativus, CsMYB60 activates the expression of the structural genes in the PA biosynthesis pathway by binding to the promoter of CsLAR , which subsequently impacts PA accumulation . Targeting the DkANR , DkMYB2 , and DkMYB20 influences the biosynthesis of PAs, with the decreased expression of these genes resulting in a decline in PA accumulation, whereas their overexpression leads to the induction of PAs in persimmon leaf calli. , The MdMYB9/11 and MdbHLH3 modules, which bind to the promoters of MdLAR and MdANR , contribute to substantial levels of PAs when ectopically expressed in apple calli . Similarly, MdMYB12 interacts with MdbHLH33 to significantly enhance the transcriptional activity of the MdLAR promoter and stimulates PA accumulation in apple calli .…”

A TCP Transcription Factor in Malus halliana, MhTCP4, Positively Regulates Anthocyanins Biosynthesis

“…The empty vector pGreenII 62-SK was used as a negative control effector. Transformation and infiltration were performed as described in Yang et al [ 48 ]. The luciferase signals were observed by an imaging apparatus (Plant View 100, Guangzhou, China).…”

Reinforcing the bulwark: unravelling the efficient applications of plant phenolics and tannins against environmental stresses

“…All these reactions might point to stress prevention role, possibly against reactive oxygen species (ROS), which are frequently produced during plant stress responses. The DkMYB 2 CT controller reacts to injury in Diospyros kaki , together with the CT biosynthetic genes, indicating that D. kaki CTs could be inducible ( Yang et al., 2020 ).…”