Genome sequence and RNA-seq analysis reveal genetic basis of flower coloration in the giant water lilyVictoria 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 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 N50 of 14.3 Mbp and a total assembly size of 3.54 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 pinkish stage of a flower. Structural genes with expression differences between white and pinkish flower stages include VcrF3’H, VcrF3’5’H, VcrDFR, VcrANS , and VcrarGST . The expression pattern of the corresponding transcription factors VcrMYBSG5, VcrMYBSG6, VcrTT8 , and VcrTTG1 also showed differences that aligned with the flower color.