Alterations of Phenylpropanoid Biosynthesis Lead to the Natural Formation of Pinkish-Skinned and White-Fleshed Strawberry (Fragaria × ananassa)

Abstract

Anthocyanin content is important for both the external and internal fruit quality of cultivated strawberries, but the mechanism of its accumulation in pinkish-skinned and white-fleshed strawberries is puzzling. Here, we found that the factor determining variation in the flesh color was not the FaMYB10 but the FaC4H in the cultivated strawberry Benihoppe and its white-fleshed mutant Xiaobai. Compared with Benihoppe, there was no significant difference in the coding sequence and expression level of FaMYB10 in Xiaobai’s flesh. Instead, the transcription of FaC4H was dramatically inhibited. The combined analyses of transcriptomics and metabolomics showed that the differential genes and metabolites were significantly enriched in the phenylpropanoid biosynthesis pathway. Furthermore, the transient overexpression of FaC4H greatly restored anthocyanins’ accumulation in Xiaobai’s flesh and did not produce additional pigment species, as in Benihoppe. The transcriptional repression of FaC4H was not directly caused by promoter methylations, lncRNAs, or microRNAs. In addition, the unexpressed FaF3′H, which resulted in the loss of cyanidin 3-O-glucoside in the flesh, was not due to methylation in promoters. Our findings suggested that the repression of FaC4H was responsible for the natural formation of pinkish-skinned and white-fleshed strawberries.

Heterozygous frameshift mutation in FaMYB10 is responsible for the natural formation of red and white-fleshed strawberry (Fragaria x ananassa Duch)

“…Jiang et al. also performed comparative transcriptomic analysis of HJ and XB ripe fleshed, and suggested that the repression of FaC4H was responsible for lack of anthocyanin in XB ripe flesh ( Jiang et al., 2022 ). FaC4H is a key gene in the phenylpropanoid metabolic pathway.…”

“…However, FaUFGT was clearly differentially expressed (upregulated more than twenty-fold), suggesting that it contributed to the different flesh colors between HJ and XB. Jiang et al also performed comparative transcriptomic analysis of HJ and XB ripe fleshed, and suggested that the repression of FaC4H was responsible for lack of anthocyanin in XB ripe flesh (Jiang et al, 2022). FaC4H is a key gene in the phenylpropanoid metabolic pathway.…”

Genome-wide identification and expression profiling reveal the regulatory role of U-box E3 ubiquitin ligase genes in strawberry fruit ripening and abiotic stresses resistance

“…The relative expression of FaU-box genes was calculated using the 2 -ΔΔCt method ( Livak and Schmittgen, 2001 ). FaActin (accession: LC017712) and 26-18S interspacer RNA ( Jiang et al., 2022 ) were used as the reference genes to normalize the raw expression data. All data were represented by the mean ± standard deviation (SD) of three independent biological replicates.…”

Proanthocyanidins Delay Fruit Coloring and Softening by Repressing Related Gene Expression during Strawberry (Fragaria × ananassa Duch.) Ripening

“…At least two well replicates were performed for each sample, and threeindependent cDNA samples were used as three biological replicates. The primers of flavonoid-related and housekeeping genes were the same as used in a previous study [ 64 ]; other primers were designed using NCBI online tool; all primers are listed in Supplementary Table S1 .…”