Identification of CDF family members in apple and their expression in response to sucrose during floral induction

Plant-specific CDF genes encode a class of transcription factors which play crucial roles in plant flowering, especially in photoperiod-regulated flowering. But little is known about the potential functions ofMdCDFs during flower induction in apple. In this study, 11 putativeMdCDFs were identified and named systematically. Bioinformatic analysis revealed a functional and structural similarity among theMdCDFs. Analysis of tandem and synteny revealed several pairedCDFhomologs between apple andArabidopsis. RT-qPCR revealed thatMdCDFs exhibited distinct expression patterns in different apple tissues and most of them displayed high expression levels in flowers and leaves. Further expression profiles ofMdCDFs were investigated in different-flowering varieties of apple and in response to sugar treatment. The results indicated thatMdCDFs were responsive to floral induction. Meanwhile, the expressions of allMdCDFs were inhibited in buds during different floral induction stages after sugar treatment. The expressions of flowering-related and photoperiod pathway-related genes showed differences and may indicate that most of theMdCDFs may function as a light response flowering inhibitor and could be repressed by the sugar-mediated floral induction. Collectively, the comprehensive analysis ofMdCDFs provides valuable information on their expression during floral induction that will serve as a foundation for further studies.