Genome-Wide Analysis of MYB10 Transcription Factor in Fragaria and Identification of QTLs Associated with Fruit Color in Octoploid Strawberry

The genus Fragaria encompass fruits with diverse colors influenced by the distribution and accumulation of anthocyanin. Particularly, the fruit colors of strawberries with different ploidy levels are determined by expression and natural variations in the vital structural and regulatory genes involved in the anthocyanin pathway. Among the regulatory genes, MYB10 transcription factor is crucial for the expression of structural genes in the anthocyanin pathway. In the present study, we performed a genome wide investigation of MYB10 in the diploid and octoploid Fragaria species. Further, we identified seven quantitative trait loci (QTLs) associated with fruit color in octoploid strawberry. In addition, we predicted 20 candidate genes primarily influencing the fruit color based on the QTL results and transcriptome analysis of fruit skin and flesh tissues of light pink, red, and dark red strawberries. Moreover, the computational and transcriptome analysis of MYB10 in octoploid strawberry suggests that the difference in fruit colors could be predominantly influenced by the expression of MYB10 from the F. iinumae subgenome. The outcomes of the present endeavor will provide a platform for the understanding and tailoring of anthocyanin pathway in strawberry for the production of fruits with aesthetic colors.

The Structure and Methylation Level of the McMYB10 Promoter Determine the Leaf Color of Malus Crabapple

Anthocyanins are protective pigments that accumulate in plant organs such as fruits and leaves, and are nutritionally valuable components of the human diet. The MYB10 transcription factor (TF) plays an important role in regulating anthocyanin biosynthesis in Malus crabapple leaves. However, little is known about how the promoter regulates McMYB10 expression and influences the substantial variation in leaf anthocyanin accumulation and coloration that is observed in different crabapple cultivars. In this study, we analyzed leaf coloration, anthocyanin levels, and the expression levels of McMYB10 in the leaves of 15 crabapple cultivars with three leaf colors at various development stages, and showed that the expression of McMYB10 correlates positively with anthocyanin accumulation. We also examined the relationship between the number of R6 and R1 elements in the McMYB10 promoters of the different cultivars and the pigmentation of the new buds of spring-red cultivars, as well as the methylation level of the McMYB10 promoters at different development stages in three representative crabapple cultivars. The ratio of R6/R1 minisatellites in the promoters correlated with the color and anthocyanin accumulation in new crabapple buds, and we concluded that the differences in promoter structure and methylation level of the McMYB10 promoters coordinately affect the leaf color of crabapple cultivars.