Molecular genetics of blood‐fleshed peach reveals activation of anthocyanin biosynthesis by NAC transcription factors

Abstract

SUMMARYAnthocyanin pigmentation is an important consumer trait in peach (Prunus persica). In this study, the genetic basis of the blood-flesh trait was investigated using the cultivar Dahongpao, which shows high levels of cyanidin-3-glucoside in the mesocarp. Elevation of anthocyanin levels in the flesh was correlated with the expression of an R2R3 MYB transcription factor, PpMYB10.1. However, PpMYB10.1 did not co-segregate with the blood-flesh trait. The blood-flesh trait was mapped to a 200-kb interval on peach linkage group (LG) 5. Within this interval, a gene encoding a NAC domain transcription factor (TF) was found to be highly up-regulated in blood-fleshed peaches when compared with non-red-fleshed peaches. This NAC TF, designated BLOOD (BL), acts as a heterodimer with PpNAC1 which shows high levels of expression in fruit at late developmental stages. We show that the heterodimer of BL and PpNAC1 can activate the transcription of PpMYB10.1, resulting in anthocyanin pigmentation in tobacco. Furthermore, silencing the BL gene reduces anthocyanin pigmentation in blood-fleshed peaches. The transactivation activity of the BL-PpNAC1 heterodimer is repressed by a SQUAMOSA promoter-binding protein-like TF, PpSPL1. Low levels of PpMYB10.1 expression in fruit at early developmental stages is probably attributable to lower levels of expression of PpNAC1 plus the presence of high levels of repressors such as PpSPL1. We present a mechanism whereby BL is the key gene for the blood-flesh trait in peach via its activation of PpMYB10.1 in maturing fruit. Partner TFs such as basic helix-loop-helix proteins and NAC1 are required, as is the removal of transcriptional repressors.

Abscisic Acid Regulates Anthocyanin Biosynthesis and Gene Expression Associated With Cell Wall Modification in Ripening Bilberry (Vaccinium myrtillus L.) Fruits

“…Recently, a PpBL gene (BLOOD) was indicated as a key regulator of anthocyanin biosynthesis in maturing blood-fleshed peach fruit (Zhou et al, 2015). It was shown to act as a heterodimer with another NAC family member, PpNAC1 (Zhou et al, 2015).…”

“…Recently, a PpBL gene (BLOOD) was indicated as a key regulator of anthocyanin biosynthesis in maturing blood-fleshed peach fruit (Zhou et al, 2015). It was shown to act as a heterodimer with another NAC family member, PpNAC1 (Zhou et al, 2015). In our study, the closest bilberry homolog for the peach BL gene, VmBL , showed a significant induction in its expression by ABA treatments as well as increased expression at the onset of bilberry fruit ripening slightly before VmTDR4 .…”

Substantial Epigenetic Variation Causing Flower Color Chimerism in the Ornamental Tree Prunus mume Revealed by Single Base Resolution Methylome Detection and Transcriptome Sequencing

“…A study of blood-fleshed P. persica uncovered a mechanism whereby BLOOD ( BL ) was the key gene for the blood-fleshed trait via its activation of PpMYB10.1 , and the silencing of BL reduced anthocyanin pigmentation in maturing fruits [6]. The MYB10 promoter is more variable in Malus × domestica “Honeycrisp” than in “Royal Gala”, which results in a more variable color pattern in the peel of the first cultivar [36].…”

“…The resulting somatic cell lines contain pigments, including flavonoid, carotenoid, and betalain secondary metabolites, that can be directly visualized [4,5,6,7]. At the molecular level, chimeric variation was initially explained by the action of transposable elements (TEs, or transposons), or, more specifically, the Activator / Dissociation ( Ac / Ds ) system that regulates the mixture of purple and yellow pigments in maize kernels by activating or repressing a C group gene [8].…”

Knockdown of Carotenoid Cleavage Dioxygenase 4 (CCD4) via Virus-Induced Gene Silencing Confers Yellow Coloration in Peach Fruit: Evaluation of Gene Function Related to Fruit Traits

“…Furthermore, Wang et al (2013) triggered the transcriptional gene silencing with TRV-based virus vectors in the young pear fruit skin. More recently, one report on TRV-based gene silencing in peach fruits was published in which silencing of NAC by VIGS led to the bleaching of the red-fleshed peach (Zhou et al 2015). Thus, plant virus vectors offer an attractive alternative method to study gene function especially related to fruit traits as well as to create transgenic plants especially in case of transformation-recalcitrant fruit trees.…”