Abstract
Blueberry is rich in anthocyanins which accumulate during fruit maturation. Previous studies mostly focus on their translational/transcriptional regulation, but usually underestimate their post-transcriptional regulation, e.g. small RNAs. This study aimed to identify sRNAs and their potential pathways associated with anthocyanin biosynthesis. During three typical phases of fruit maturation (green, pink, and blue), we investigated dynamic changes of sRNA by deep sequencing sRNA and examined the interaction of sRNAs with their target genes by degradome and RLM-PCR. During maturation, up-regulation of VcmiRNA156 and VcmiR393 resulted in down-regulation of VcSPLs and VcTIR1/AFBs, respectively. An important gene of anthocyanin biosynthesis, VcDFR, was substantially down-regulated at both the mRNA and protein levels, and potentially responded to regulation of VcSPLs and VcTIR1/AFBs. Additionally, indole acetic acid (IAA) and abscisic acid (ABA) were involved in the regulation of anthocyanin biosynthesis by interacting with VcmiR393-TIR1/AFBs and VcmiRNA319-VcMYBs respectively. This information provides another insight into blueberry anthocyanin biosynthesis.
Highlights
Blueberry is rich in anthocyanins which accumulate during fruit maturation
Flavonoid biosynthesis begins with chalcone synthase (CHS) working on the condensation of three molecules of malonyl CoA and one of p-coumaroyl CoA synthesized from phenylalanine
O-methyltransferases (OMTs) catalyze the formation of O-methylated anthocyanins such as malvidin, peonidin, and petunidin. The transcription of these structural genesis usually regulated by three types of transcription factors (TFs) together, i.e. DNA-binding R2R3 MYB, MYC-like basic helix–loop–helix and WD40-repeats[4,5], Another subset of TFs, SQUAMOSA promoter-binding protein-like (SPL/SBP) family participate in regulation of these structural genes as well[6]
Summary
Blueberry is rich in anthocyanins which accumulate during fruit maturation. Previous studies mostly focus on their translational/transcriptional regulation, but usually underestimate their post-transcriptional regulation, e.g. small RNAs. An important gene of anthocyanin biosynthesis, VcDFR, was substantially down-regulated at both the mRNA and protein levels, and potentially responded to regulation of VcSPLs and VcTIR1/AFBs. indole acetic acid (IAA) and abscisic acid (ABA) were involved in the regulation of anthocyanin biosynthesis by interacting with VcmiR393-TIR1/AFBs and VcmiRNA319-VcMYBs respectively. O-methyltransferases (OMTs) catalyze the formation of O-methylated anthocyanins such as malvidin, peonidin, and petunidin The transcription of these structural genesis usually regulated by three types of transcription factors (TFs) together, i.e. DNA-binding R2R3 MYB, MYC-like basic helix–loop–helix (bHLH or MYC) and WD40-repeats[4,5], Another subset of TFs, SQUAMOSA promoter-binding protein-like (SPL/SBP) family participate in regulation of these structural genes as well[6]. The miRNA involved in the transitions from flower, to white fruit and to blue fruit have been characterized[14]
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