Conclusions
In order to obtain better taste quality in strawberries at the moment of consumption, we analysed the dynamics of sucrose accumulation during ripening transition in strawberries and considered the way in which sucrose reserves after harvest are controlled by environmental factors. Analysis of carbohydrates and the expression of sucrose-related genes revealed that short-term treatment with high levels of CO2 is particularly efficient in the accumulation of sucrose and soluble carbohydrates, suggesting activation of a carbohydrate-conserving mode in CO2-treated strawberries. To our knowledge, this is the first time that a synchronized down-regulation of genes encoding sucrose breakdown has been highlighted, which mainly involves FvVINV homologues, with an increase in sucrose and soluble carbohydrate content. The lower expression of FvVINV2 observed in CO2-treated strawberries might be related with a less consumption of sucrose what would drive to a lower weight loss. This fact is supported not only by the negative correlation between solutes and FwVINV2 expression in air-stored strawberries, but also by the findings observed in DR strawberries. In this ripening stage, a more active sucrose metabolism is recorded relative to FR strawberries, suggesting an essential role of the date of harvest in sucrose metabolism. The decrease of sucrose at 0 ÂșC is linked to a high consumption of released hexoses due to upregulation of FvSS , FvVINV homologues and, especially,FvCWINV2 encoding genes involved in sucrose breakdown.