Abstract:

Using the‘Fuji’apple，we cloned a key transcription factor INDETERMINATE DOMAIN（IDD）family gene MdIDD7，in which had 1 626 bp of open reading frame（ORF）and encoded 541 amino acids. By the sequence alignment and domain analysis，its contained a nuclear localization signal（NLS）and four zinc finger protein conserved domains. Phylogenetic tree analysis showed that MdIDD7 gene of Malus × domestica，Pyrus × bretschneideri（XP_009364602.1），Prunus persica （XP_007225628.1），Prunus mume（XP_008220893.1）were clustered together. The MdIDD7 gene was expressed in five different tissues（stem，leaf，flower，fruit and bud） of‘Fuji’apple trees，and its expression in buds was the highest. During the days after flowering（from 40 to 60 days），the expression levels of MdIDD7 gene was significantly higher in‘Yanfu 6’than in‘Changfu 2’apple. Inaddition，the expression level of MdIDD7 gene was significantly higher in“Off-year”trees than in“On-year”trees. In the early stage of flower bud induction，the expression of MdIDD7 gene was significantly down-regulated in the exogenous GA treatment compared to water spring treatment，but was significantly up-regulated in sucrose treatment during the early stages of flower bud induction，suggesting that the MdIDD7 can promote apple flower bud formation in response to GA and sugar signaling.

Key words: apple, flowering induction, MdIDD7, gene clone, expression analysis