Metabolomic and physico-chemical approach unravel dynamic regulation of calcium in sweet cherry fruit physiology

Calcium (Ca2) nutrition has a significant role in fruit physiology; however, the underlying mechanism is still unclear. In this study, fruit quality in response to CaCl2, applied via foliar sprays (Ca2) or/and hydro-cooling water (CaHC), was characterized in 'Lapins' cherries at harvest, just after cold storage (20 days at 0 °C) as well as after cold storage followed by 2 days at 20 °C, herein defined as shelf-life period. Data indicated that pre- and post-harvest Ca2+ applications increased total Ca2+ and cell wall bound Ca2+, respectively. Treatment with Ca reduced cracking whereas Ca + CaHC condition depressed stem browning. Both skin penetration and stem removal were affected by Ca2+ feeding. Also, several color- and antioxidant-related parameters were induced by Ca2+ treatments. Metabolomic analysis revealed significant alterations in primary metabolites among the Ca2+ treatments, including sugars (eg., glucose, fructose), soluble alcohols (eg., arabitol, sorbitol), organic acids (eg.,malate, quinate) and amino acids (eg., glycine, beta-alanine). This work helps to improve our knowledge on the fruit's response to Ca2+ nutrition.