Effect of Thinning on Metabolomic Fruit Profile of an Early Harvest Peach Variety

Thinning is an agronomical practice that consists in the removal of fruits from the tree to improve the growth of the remaining ones. The reduction in the number of fruit leads to an increase of sugar assimilates that are translocated towards the remaining fruit improving its size and soluble solid content. Although it was observed an increase in soluble solids in fruits from thinned trees, which metabolites are altered and any impact on the organoleptic properties remain to be elucidated. The purpose of this work was to compare the polar metabolic profile of fruit from thinned and unthinned trees during different developmental stages including a postharvest period of an early harvest peach variety. The aforementioned analysis was carried out through the identification and quantification of sugars, sugars alcohols, aminoacids, and organic acids by gas chromatography coupled to a mass spectrometry detector (GC-MS). Multivariate analysis (partial least square regression - discriminant analysis) revealed differences between fruits from unthinned and thinned trees related to relative abundance of sugars such as fructose, glucose and sorbitol and also the aminoacids such as asparagine, leucine, phenylalanine, and threonine. Furthermore, early developmental stages displayed a clear separation from the postharvest evaluated stage due to differences in the relative amount of quinic and oxalic acids and aminoacids such as valine, serine, alanine and aspartic acid. Our results suggest that tree thinning affects different physiological aspects impacting not only fruit size but also fruit flavor. Some of the identified metabolites could be used as markers for early fruit quality segregation. Acknowledgements: FONDECYT 1130197, FONDEQUIP EQM140074, Viveros El Tambo.