Characterisation of induced Malus x domestica ‘Royal Gala’ cell differentiation by using different hormones in cell cultures

Fruit development, following pollination, involves a cell division stage, followed by cell expansion . A major challenges to study each individual stages is the limitations imposed by analyses of fruit development on the plant. Rapid growing cell culture systems that differentiate could be used to identify and understand the molecular control of each of these processes <i>in vitro</i>. In this study, an apple cell culture was initiated from the widely characterised ‘Royal Gala’ cultivar. The established apple cell culture was used to develop a screening system to assess the effect of different hormones on cell differentiation, which then were characterised at molecular and cellular levels. Three different hormone pairs were screened to determine the optimal for cell expansion on actively dividing cells . Using this strategy, we were able to reproduce, <i>in vitro</i>, the first two stages of apple fruit cell differentiation, cell division and expansion, which was correlated with changes in genes expression of specific markers for those two stages, a cyclin-dependent kinase gene (<i>CDKB2;2</i>) and an expansion gene (<i>EXP3</i>). The cell culture provides a unique tool and opportunity to study the effect of plant hormones on cell differentiation and will allow to decipher the molecular mechanism of apple fruit development irrespective of y.