Floral Pigmentation and Expression of Anthocyanin-Related Genes in Bicolored Roses ‘Pinky Girl’ as Affected by Temporal Heat Stress

This study was conducted to investigate petal pigmentation and the expression patterns of anthocyanin-related genes in bicolored roses ‘Pinky Girl’ treated with temporal heat stress (THS). Cyanin accumulation in petals was correlated with flor al bud development and started rapidly as floral buds began to open, defined as the 4 th stage of floral bud development (S 4 ). This stage seems to be most susceptible to petal pigmentation. The total of cyanin pigmentation at blooming was si gnificantly decreased (by 45.5%) with exposure to THS (39/18°C for three days at S 4 ) in comparison with control. Meanwhile, the expression of anthocyanin-related genes such as CHS, CHI, F3’H, DFR, ANS, 3GT, and 5GT was relatively promoted by THS. Only F3H was less expressed (by 26.7%) with THS treatment; thus, F3H could be a key gene for bicolor promotion in ‘Pinky Girl’ amon g anthocyanin-related genes. Overall, the expression pattern of the most anthocyanin-related genes did not match the trends of cyanin pigmentation in petals. These results suggest that floral pigmentation could be associated with other mechanisms related to anthocyanin biosynthesis such as post-translational effects and regulatory genes.Additional key words: