Abstract
BackgroundThe majority of apricot (Prunus armeniaca L.) cultivars display orange or yellow background skin, whereas some cultivars are particularly preferred by consumers because of their red blushed skin on the background.ResultsIn this study, two blushed (‘Jianali’ and ‘Hongyu’) and two nonblushed (‘Baixing’ and ‘Luntaixiaobaixing’) cultivars were used to investigate the formation mechanism of blushed skin in apricots. High-performance liquid chromatography (HPLC) analysis showed that the blushed cultivars accumulated higher cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside and peonidin-3-O-rutinoside levels during fruit ripening than the nonblushed cultivars. Based on coexpression network analysis (WGCNA), a putative anthocyanin-related R2R3-MYB, PaMYB10, and seven structural genes were identified from transcriptome data. The phylogenetic analysis indicated that PaMYB10 clustered in the anthocyanin-related MYB clade. Sequence alignments revealed that PaMYB10 contained a bHLH-interaction motif ([DE]Lx2[RK]x3Lx6Lx3R) and an ANDV motif. Subcellular localization analysis showed that PaMYB10 was a nuclear protein. Real-time qRT-PCR analysis demonstrated that the transcript levels of PaMYB10 and seven genes responsible for anthocyanin synthesis were significantly higher in blushed than in nonblushed apricots, which was consistent with the accumulation of anthocyanin. In addition, bagging significantly inhibited the transcript levels of PaMYB10 and the structural genes in ‘Jianali’ and blocked the red coloration and anthocyanin accumulation. Transient PaMYB10 overexpression in ‘Luntaixiaobaixing’ fruits resulted in the red blushed skin at the maturation stage.ConclusionsTaken together, these data reveal that three anthocyanins are responsible for the blushed skin of apricots, identify PaMYB10 as a positive regulator of anthocyanin biosynthesis in apricots, and demonstrate that blush formation depends on light.
Highlights
The majority of apricot (Prunus armeniaca L.) cultivars display orange or yellow background skin, whereas some cultivars are preferred by consumers because of their red blushed skin on the background
Our results suggest that PaMYB10 is responsible for controlling anthocyanin biosynthesis and is involved in the development of blushed skin in apricots and that the process is regulated by light
Using weighted gene coexpression network analysis (WGCNA), we identified one MYB gene and seven structural genes related to anthocyanin biosynthesis in the blue and green modules that were significantly positively correlated with cyanidin3-O-glucoside, cyanidin-3-O-rutinoside and peonidin-3O-rutinoside (Fig. 4)
Summary
The majority of apricot (Prunus armeniaca L.) cultivars display orange or yellow background skin, whereas some cultivars are preferred by consumers because of their red blushed skin on the background. Xinjiang is one of the primary centers of apricot domestication worldwide and is the main cultivation area in China; almost 200 varieties are cultivated in this region [2]. Among these varieties, some cultivars with a red blush on the orange or yellow background skin are preferred by consumers due to their beautiful color and high nutritional value [3, 4]. Understanding the regulation of anthocyanin biosynthesis in fruits is important for development of anthocyanin-rich foods for our diet
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