Abstract:

Papaya is a dioeciously herbaceous plant. Identification of flower-related genes gives us an opportunity to reveal the regulation mechanism in flowering and to improve the setting rate in papaya. In this study，the genome database of papaya was used to clone the CpFT1 gene and promoter sequences. The 525 bp CpFT1 gene sequence and 1 500 bp promoter sequence were obtained by PCR method. Sequence analysis showed that the CpFT1 gene has a 525 bp open reading frame（ORF）encoding 174 amino acids. The phylogenetic tree showed that CpFT1 and Fagus crenata FT are the closest in molecular evolution distance. Subcellular localization assays showed that the CpFT1 protein was located in the nucleus. Bioinformatics analysis showed that there were abscisic acid，gibberellin，salicylic acid and other responsive cis-acting elements in the CpFT1 promoter sequence. The expressions of CpFT1 gene in 3 different sex types of flowers，4 different flower developmental stages and various hormone treatments have been revealed by qRT-PCR method. In conclusion，the results indicate that the hormones including  abscisic acid and salicylic acid are involved in the regulation of the CpFT1 gene expression.

Key words: papaya, flower development, FT1 gene, expression regulation, hormone