Grape hyacinth (Muscari spp.) is a famous bulbous blue flower; however, few bicolor varieties are available in the market. Therefore, the discovery of bicolor varieties and understanding of their mechanisms are crucial to the breeding of new varieties. In this study, we report a significant bicolor mutant with white upper and violet lower portions, with both parts belonging to a single raceme. Ionomics showed that pH and metal element contents were not responsible for the bicolor formation. Targeted metabolomics illustrated that the content of the 24 color-related compounds was significantly lower in the upper part than that in the lower part. Moreover, full-length transcriptomics combined with second-generation transcriptomics revealed 12,237 differentially expressed genes in which anthocyanin synthesis gene expression of the upper part was noted to be significantly lower than that of the lower part. Transcription factor differential expression analysis was used to describe the presence of a pair of MaMYB113a/b sequences, with low levels of expression in the upper part and high expression in the lower part. Furthermore, tobacco transformation confirmed that overexpression of MaMYB113a/b can promote anthocyanin accumulation in tobacco leaves. Accordingly, the differential expression of MaMYB113a/b contributes the formation of a bicolor mutant in Muscari latifolium.
Keywords: MYB; flower color; grape hyacinth; ionomics; metabolomic; mutant; transcriptomic.