Response of miR156-SPL Module during the Red Peel Coloration of Bagging-Treated Chinese Sand Pear (Pyrus pyrifolia Nakai)

Abstract

MicroRNA156 is an evolutionarily highly conserved plant micro-RNA (miRNA) that controls an age-dependent flowering pathway. miR156 and its target SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes regulate anthocyanin accumulation in plants, but it is unknown whether this process is affected by light. Red Chinese sand pear (Pyrus pyrifolia) fruits exhibit a unique coloration pattern in response to bagging treatments, which makes them appropriate for studying the molecular mechanism underlying light-induced anthocyanin accumulation in fruit. Based on high-throughput miRNA and degradome sequencing data, we determined that miR156 was expressed in pear fruit peels, and targeted four SPL genes. Light-responsive elements were detected in the promoter regions of the miR156a and miR156ba precursors. We identified 19 SPL genes using the “Suli” pear (Pyrus pyrifolia Chinese White Pear Group) genome database, of which seven members were putative miR156 targets. The upregulated expression of anthocyanin biosynthetic and regulatory genes and downregulated expression of PpSPL2, PpSPL5, PpSPL7, PpSPL9, PpSPL10, PpSPL13, PpSPL16, PpSPL17, and PpSPL18 were observed in pear fruits after bags were removed from plants during the anthocyanin accumulation period. Additionally, miR156a/ba/g/s/sa abundance increased after bags were removed. Yeast two-hybrid results suggested that PpMYB10, PpbHLH, and PpWD40 could form a protein complex, probably involved in anthocyanin biosynthesis. Additionally, PpSPL10 and PpSPL13 interacted with PpMYB10. The results obtained in this study are helpful in understanding the possible role of miR156 and its target PpSPL genes in regulating light-induced red peel coloration and anthocyanin accumulation in pear.

PbMYB120 Negatively Regulates Anthocyanin Accumulation in Pear

“…Meanwhile, anthocyanin activators and repressors are also induced or inhibited after short-or long-term stress treatments [45]. Light exposure also induces anthocyanin accumulation [18,46,47]. In this study, the MYB activators PbMYB10 and PbMYB10b and the MYB repressor PbMYB120 were all induced after light exposure.…”

Integrated sRNAome and RNA-Seq Analysis Reveals miRNA Effects on Betalain Biosynthesis in Pitaya

“…The percentage of 24 nt sRNAs (an average of 58.03%) was much higher than that of 21 nt sRNAs (an average of 12.16%) in pitaya pulp ( Figure S1). The result was consistent with the length distribution of sRNAs in apple and litchi [15,20,58], but was inconsistent with the ndings in strawberry, orange, Brassica juncea, and apple [ [13,20,21,23]. Bgy-mir156 regulates the target gene phytoene synthase (PSY) and affects the accumulation of carotenoids in carrot (Daucus carota) [12].…”

“…For example, the predicted target genes of Hmo-miR529b were found to be involved in squamosa promoterbinding-like protein 6 (SPL6), histone-lysine N-methyltransferase and ubiquitin-protein ligase. Based on transcriptome annotation, six targets involved in betalain biosynthesis were selected [23,[40][41][42]. Among them, HmCYP83B1-like, HmCYP71A8-like, HmTPST-like, HmWDTC1-like and HmSPL16-like were respectively targeted by Hmo-novel-2, Hmo-miR6020, Hmo-novel-15, Hmo-miR164a and Hmo-miR156 while HmSPL6-like was co-targeted by Hmo-miR156, Hmo-miR157b and Hmo-miR529b.…”

“…In different rose cultivars, miRNAs may negatively regulate target genes to prevent carotenoid accumulation resulting in white owers according to expression analyses of ve miRNAs [9]. miRNAs can also regulate anthocyanin accumulation through their target genes [13][14][15][16][17][18][19][20][21][22][23][24][25].…”

Integrated sRNAome and RNA-Seq Analysis Reveals miRNA Effects on Betalain Biosynthesis in Pitaya

“…Generally, conserved miRNAs had the same or homologous targets as other plant species, and most of them have a similar function. MIR156 plays key role in the biosynthesis of secondary metabolites.MIR156 can positively regulate anthocyanin biosynthesis by SPL TFs, while SPL TFs negatively regulate anthocyanin accumulation in Arabidopsis, apple, litchi, and Pyrus pyrifolia[13,20,21,23].…”