Genome sequence and RNA-seq analysis reveal genetic basis of flower coloration in the giant water lily Victoria cruziana

Victoria cruziana is well known for its huge floating leaves covered with sharp spines and its night blooming. Reports indicate that white flowers open during the first night and turn light pinkish during the following day and the second night. Here, we set out to unravel the molecular basis and ecological function of the flower color change in V. cruziana. A high quality genome sequence with a contig N50 of 44.2 Mbp, a scaffold N50 of 300 Mbp, and a total assembly size of 3.5 Gbp was generated as the genetic basis for this study. Comparative transcriptomics revealed the genes required for anthocyanin biosynthesis genes and their transcriptional regulators as differentially expressed between the white and the light pinkish stage of a flower. Structural genes with expression differences between white and light pinkish flower stages include VcrF3H, VcrF35H, VcrDFR, VcrANS, and VcrarGST. The expression pattern of the corresponding transcription factors VcrMYB123, VcrMYB-SG6_a, VcrMYB-SG6_b, VcrTT8, and VcrTTG1 also showed differences that aligned with the flower color.