Characterization Of Phenolic Compounds In 19 Malus Genotypes

Phenolic compounds wildly exist in tissues of Malus genotypes,playing an important role in growth and reproduction.For human beings,intake of these compounds can reduce risk of many diseases.The aim of this study was to investigate the phenolic compounds composition and content in leaves,flowers,and fruits of Malus germplasm,to discover genotypes rich in phenolics,providing guidance for exploitation of phenolics in all tissues of Malus germplasm and for breeding apple cultivars rich in phenolics.Phenolic compounds were identified and quantified in leaves,flowers,and fruits of 19 Malus genotypes using reversed phase high performance liquid chromatography?RP-HPLC?.The main results are as follow:In all genuses,16 phenolic compounds were detected in different Malus plant tissues,including 2 phenolic acids?gallic acid and chlorogenic acid?,3 dihydrochalcones?phlorizin,trilobatin and siebodin?,4 flavanols?catechin,epicatechin,procyanidin B1,and procyanidin B2?,6 flavonols?quercetin-3-galactoside,quercetin-3-rutinoside,quercetin-3-glucoside,quercetin-3-arabinoside,quercetin-3-rhamnoside,and quercetin?,and 1 anthocyanin?cyanidin-3-galactoside?.Among the detected genotypes,Malus ‘Adams' did not contain any phlorizin;domestic cultivars had no trilobatin and siebadin,which were reported for the first time.Siebodin was observed in fruits of M.‘Pink Spires',M.‘Kelsey',and M.‘Radiant',but not in leaves and flowers of these genotypes.The total concentrations of phenolic acids,dihydrochalcones,flavanols,flavonols,and anthocyanins were 2086.20-8834.87,31045.03-66229.36,1590.00-14926.57,1850.11-19161.31,and 10.42-22131.31 mg kg^-1 FW,respectively.Among phenolics,the contents of flavanols,flavonols,and anthocyanins had significant differences in different genotypes.The concentrations of flavanols were more than 10000 mg kg^-1 FW in M.micromalus ‘Haihong Fruit',M.‘Red Splender',and M.‘Sparkler';the contents of flavonols were less than 10000 mg kg^-1 FW in all genus Malus,except M.domestic ‘Golden Delicious';anthocyanin mainly existed in the red leaves,flowers,and fruits,especially,the concentrations of anthocyanin in ornamental crabapple cultivars?M.‘Kelsey',M.‘Royalty',M.‘Radiant',and M.‘Sparkler'?were more than 10000 mg kg^-1 FW.Quercetin-3-galactoside was the predominant glycoside form in most genotypes,while concentration of cyaniding-3-galactoside was significant higher than that of cyaniding-3-glucoside in all genus Malus.In general,the concentration of total phenolics was highest in leaves,followed by flowers and fruits.Flavonols and dihydrochalcones largely existed in leaves;chlorogenic acid was higher in flowers and fruits than in leaves,respectively;flavanols mainly occurred in fruits;concentrations of anthocyanins in flowers were highest among all tissues.In this study,there were abundant phenolic compounds in leaves,flowers,and fruits of 19 Malus genotypes,with contents varied depend on the species and the tissue type.Small amounts of quercetin aglycones were present,with the water-soluble glycoside forms predominating in different Malus plant tissues.These results may provide useful information for apple breeding and artificial extraction of phenolic compounds.