Abstract: Freesia hybrida‘Shangnong Jinhuanghou’was used to investigate the organ-specific and time-course expression of 1-aminocyclopropane-1-carboxylate synthase gene FhACS1 in Freesia flowers. The results showed that significant differences presented in FhACS1 gene expression in different floral organs，florets at different developmental stage and florets during vase time. The organ-specific expression pattern of FhACS1 gene showed that the highest and the lowest expression were observed in stamens and pistil，respectively. The expression pattern of FhACS1 gene in florets at different developmental stages suggested that the highest and the lowest expression was observed in floret fully open（stage 0）and in florets at stage 4，respectively. To study the time-course expression pattern of FhACS1 gene in Freesia florets，the 3rd and 6th bud on inflorescence were used. The results suggested the expression in the 6th bud was significantly higher than that in the 3rd bud. For the 3rd bud，the expressions in petals，stamens and pistil were first increased and then decreased，but the highest expression in each floral organ occurred at different time；expression pattern in whole bud was consistent with that in petal. For the 6th bud，expressions of FhACS1 gene continued to rise in petals，and first increased and then decreased in stamens and pistil；the highest expressions in stamens and pistil occurred at the 3th and 6th day，respectively；the expression pattern in whole bud was similar with that in petals.

Key words: Freesia, 1-aminocyclopropane-1-carboxylate synthase, floral organs, senescence, gene expression