Postharvest changes in primary and secondary metabolites of sweet cherry cultivars induced by Monilinia laxa

The aim of the study was to evaluate in which way nine cultivars of sweet cherry fruit cope with postharvest, artificial inoculation with Monilinia laxa pathogenic fungus through changes in sugars, organic acids and polyphenolic compounds, as well as which phenolics compounds are crucial participants in coping with the disease. Contents of sugars in this study were (g kg(-1) dry weight): glucose 205-439 and 268-443, fructose 175-398.9 and 208.6-365.8 and sucrose 20-47.6 and 19.2-38.6 in healthy and infected fruit, respectively. Organic acids detected in sweet cherry cultivars were citric, malic, quinic, shikimic and fumaric acid and their content varied depending on cultivar and treatment. Only 'Burlat' accumulated tartaric acid after the infection. Of all phenolic acids, which content decreased in infected fruit, it is clear that only the more tolerant genotypes 'Merchant', 'Lionska', and 'Sue' enhanced content of 3-feruloylquinic acid (in healthy up to 93 and in infected fruit 105.3-139.1 mg kg(-1)). The most abundant anthocyanins were cyanidin derivatives (80-266.1 and 10-3700 mg kg(-1) in healthy and infected fruit, respectively). 'Burlat', 'Junska rana', 'Merchant' and 'Summit' dominantly had cyanidin-glucoside, while only infected fruit of 'Priusadebnaja' and 'Asenova rana' accumulated cyanidin-glucoside. 'Priusadebnaja', 'Asenova rana' and 'Lionska' had cyanidin-rutinoside. 'Lionska', 'Sue' and 'Asenova rana' had higher cyanidin and peonidin derivative contents in infected fruit (1.2 to 3-fold higher). Peonidine derivatives (peonidin glucoside and rutinoside), 5-carboxypyrano-cyanidin-rutinoside content mostly decreased after the infection (14.9-97.7 %). Bearing in mind obtained results, 3-feruloylquinic acid, flavonols and anthocyanins could be proposed as crucial participants in coping with the disease.