Identification of Candidate Genes Responsible for Flower Colour Intensity in .

Gentians cultivated in Japan ( and and hybrids) have blue flowers, but flower colour intensity differs among cultivars. The molecular mechanism underlying the variation in flower colour intensity is unclear. Here, we produced F progeny derived from an F cross of intense- and faint-blue lines and attempted to identify the genes responsible for flower colour intensity using RNA-sequencing analyses. Comparative analysis of flower colour intensity and transcriptome data revealed differentially expressed genes (DEGs), although known flavonoid biosynthesis-related genes showed similar expression patterns. From quantitative RT-PCR (qRT-PCR) analysis, we identified two and four genes with significantly different expression levels in the intense- and faint-blue flower lines, respectively. We conducted further analyses on one of the DEGs, termed , which encodes a putative mini zinc-finger protein homolog, which was most differently expressed in faint-blue individuals. Functional analysis of was performed by producing stable tobacco transformants. -overexpressing tobacco plants showed reduced flower colour intensity compared with untransformed control plants. DNA-marker analysis also confirmed that the allele of the faint-blue flower line correlated well with faint flower colour in F progeny. These results suggest that is one of the key genes involved in determining the flower colour intensity of gentian.