Fruits develop differently in herbaceous and woody species

It’s soluble sugars in the pulp that give the fruits their taste. Coffi Cakpo and colleagues have sought to get a better understanding of fruit development by modelling the accumulation of sugars across ten fruit species.

“Understanding the differences and similarities of sugar accumulation strategies across fruit species can help to identify key physiological processes, common regulatory mechanisms as well as possible trade-offs, in the perspective of improving fruit quality (Roch et al. 2019). In spite of such a potential, only few works have addressed the issue of species comparison to date. One reason for this resides in the difficulty of resuming differences both in the nature of the physiological process involved (diversity of the molecules and enzymes) as well as in their duration, across different species,” write the authors.

Statistical analyses based on metabolic rates separated the species into six groups according to the rate of synthesis of compounds other than sugar and starch. Herbaceous species (cucumber, tomato, eggplant, pepper and strawberry) were characterized by a higher synthesis rate than woody species (apple, nectarine, clementine, grape and kiwi). Inspection of the dynamics of the processes involved in sugar accumulation revealed that net sugar importation, metabolism and dilution processes were remarkably synchronous in most herbaceous plants, whereas in kiwifruit, apple and nectarine, processes related to starch metabolism were temporally separated from other processes. Strawberry, clementine and grape showed a distinct dynamic compared to all other species.

“The results obtained in this study represent a first step in order to understand the modes of the regulation of the major processes involved in sugar accumulation,” say Cakpo and colleagues. “In a next step, it would be interesting to dissociate the acids from the cell walls in the model in order to better assess the respective contribution to carbohydrates accumulation during the early phases of fruit development.”