Transcriptional Landscape of the Apple Shoot Apex

The regulation of floral initiation in woody perennial plants, such as apple, is a complex pathway that has previously been studied only at the physiological level. The lack of knowledge about underlying molecular mechanisms has limited the ability to manipulate flowering to overcome production problems such as juvenility, over-cropping and alternate bearing. Here, we analyzed gene expression patterns associated with floral initiation in apple through transcriptional profiling of a seasonal developmental gradient of the shoot apical meristem. We also characterized the flowering-promotive effect of fruit removal and flowering-repressive effect of applied gibberellins (GAs) on gene expression. Our resulting data, containing nearly 1E11 bases of transcribed genes, represents one of the most comprehensive analysis of gene expression associated with floral initiation in a woody perennial plant to date.