Tissue-Specific Expression Analysis of Anthocyanin Biosynthetic Genes in White- and Red-Fleshed Grape Cultivars

Abstract

Yan73, a teinturier (dyer) grape variety in China, is one of the few Vitis vinifera cultivars with red-coloured berry flesh. To examine the tissue-specific expression of genes associated with berry colour in Yan73, we analysed the differential accumulation of anthocyanins in the skin and flesh tissues of two red-skinned grape varieties with either red (Yan73) or white flesh (Muscat Hamburg) based on HPLC-MS analysis, as well as the differential expression of 18 anthocyanin biosynthesis genes in both varieties by quantitative RT-PCR. The results revealed that the transcripts of GST, OMT, AM3, CHS3, UFGT, MYBA1, F3'5'H, F3H1 and LDOX were barely detectable in the white flesh of Muscat Hamburg. In particular, GST, OMT, AM3, CHS3 and F3H1 showed approximately 50-fold downregulation in the white flesh of Muscat Hamburg compared to the red flesh of Yan73. A correlation analysis between the accumulation of different types of anthocyanins and gene expression indicated that the cumulative expression of GST, F3'5'H, LDOX and MYBA1 was more closely associated with the acylated anthocyanins and the 3'5'-OH anthocyanins, while OMT and AM3 were more closely associated with the total anthocyanins and methoxylated anthocyanins. Therefore, the transcripts of OMT, AM3, GST, F3'5'H, LDOX and MYBA1 explained most of the variation in the amount and composition of anthocyanins in skin and flesh of Yan73. The data suggest that the specific localization of anthocyanins in the flesh tissue of Yan73 is most likely due to the tissue-specific expression of OMT, AM3, GST, F3'5'H, LDOX and MYBA1 in the flesh.

Keywords: Vitis vinifera; anthocyanin; colour; flesh; gene expression; grapevine; skin; tissue specificity.

Figure 1

Expression patterns of anthocyanin biosynthetic genes in the skin and flesh of Yan 73 and Muscat Hamburg cultivars across five developmental stages. The data are derived from qPCR analysis and are normalized to VvUbiquitin. The transcriptional levels of the same gene in the skin and flesh tissues of Yan 73 and Muscat Hamburg are expressed on the y axes with the same scale, and relatively lower values are magnified in inset graphs with y axes with narrower scales. Berry developmental stage is referred to on the x axis. DAA, days after anthesis; 61 DAA (63 DAA) pre-véraison; 74 DAA (76 DAA), 50% véraison green; 82 DAA (90 DAA), 50% véraison red; 92 DAA (105 DAA), 100% véraison; 101 DAA (112 DAA) , harvest. Error bars illustrate the standard errors for three replicates.

Figure 2

Expression patterns of anthocyanin biosynthetic genes in the skin and flesh of Yan 73 and Muscat Hamburg cultivars across five developmental stages. The data are derived from qPCR analysis and are normalized to VvUbiquitin. The transcriptional levels of the same gene in the skin and flesh tissues of Yan 73 and Muscat Hamburg are expressed on the y axes with the same scale, and relatively lower values are magnified in inset graphs with y axes with narrower scales. Berry developmental stage is referred to on the x axis. DAA, days after anthesis; 61 DAA (63 DAA) pre-véraison; 74 DAA (76 DAA), 50% véraison green; 82 DAA (90 DAA), 50% véraison red; 92 DAA (105 DAA), 100% véraison; 101 DAA (112 DAA), harvest. Error bars illustrate the standard errors for three replicates.

Figure 3

Heat map of the clustered correlations between anthocyanin accumulation patterns and gene expression in Yan73. Five sampling stages, three biological replicates, skin and flesh tissues were treated as independent factors in anthocyanin-transcript pairwise comparisons, which were carried out for 30 transcriptional data points for each gene. The correlation between anthocyanin accumulation and gene expression was calculated using Pearson’s correlation coefficient. The r and P values of the correlation are given in the Supplementary Materials (Table S1).