Fig. 7

Main metabolic, hormonal and redox status regulations revealed by microarray analyses comparing differentially expressed transcripts in apical buds of spurs sampled on adult ‘Gala’ apple trees, between ‘ON’ (fruited) and ‘OFF’ (deflowered) trees. In apical buds of ‘ON’ trees, more likely to be in vegetative state, transcripts highlighted responses to stresses such as starvation for sucrose and phosphates, stress hormonal signaling and down-regulated cell detoxification processes, whereas transcripts homologous to genes known as repressor of flowering induction (such as TEMPRANILLO 1) and involved in SAM maintenance in the vegetative state (such as KNAT and NAM) were up-regulated. In apical buds of ‘OFF’ trees, more likely to be induced to flower, transcripts showed active cell biogenesis and detoxification, with several promoters of floral induction (such as FTM1 and SPL transcripts) up-regulated. Timing and transitions stages from vegetative state (Insert a) to domed meristem (stage 2, from day 203, Insert b) and floral meristem (State 4, Insert c), as defined by Foster et al. [29] are exemplified by photos of histological longitudinal sections in apical buds of ‘Gala’ apple trees