Dynamic Change Of Phenolic Compounds Of Malus 'Radiant' Leaves In Different Development Stage

As a kind of important secondary metabolites,phenolic compounds wildly distribute in plants,which not only exert indispensable biofuctions in plant development,also make a great contribution in keeping human health.This study has inveasigated phenolics changes of Malus ‘radiant' leaves in different development stages and in the treatment of ethephon and the results preliminarily pave the way for researching metabolite mechanism and biofunction of phenolic compounds,and for breeding apple cultivars rich in phenolic compounds.The experiment systematically detected content of phenolic compounds of Malus ‘radiant' leaves in different development stages and in the treatment of ethephonusing HPLC,the main results are as follows:1.There are 18 phenolic compounds being detected during leaf expand period,they are 4 dihydrochalcones(phlorizin,trilobatin,3-hydroxylphloridzin,siebodin),4 flavanols(catechin,epicatechin,procyanidin B1,and procyanidin B2),3 phenolic acids(gallic acid,chlorogenic acid,ferulic acid),6 flavonols(quercetin-3-galactoside,quercetin-3-rutinoside,quercetin-3-glucoside,quercetin-3-arabinoside,quercetin-3-rhamnoside,and quercetin-xyloside),and 1 anthocyanin(cyanidin-3-galactoside).Similar results was found in different seasonal except that the 4 phenolic acids(gallic acid,chlorogenic acid,ferulic acid,syringic acid)were detected.Likely,all of phenolic compounds was presented in stress condition within ethephon treatment.Differences in this stage is that 6 phenolic acids(gallic acid,chlorogenic acid,ferulic acid,syringic acid,caffeic acid,P-coumaric acid)were detected.2.At different development stage,the content of trilobatin is highest in dihydrochalcones,which is similar to chlorogenic acid in phenolic acids and quercetin-galactoside in flavonols,but there is no significance differences in the content of 4 flavanols.Almost phenolic content have a decrease in leave expand period except that no significance differences in the bare content of gallic acid and ferulic acid,which may result from the synthesis rate of phenolic compounds far fall behind the leave grow rate.In different growth stage,the maximum content had come nearby August in 6 flavonols and 4 phenolic acids,their whole seasonal dynamic change is increasing followed by decreasing,which shows that the high temperature in August has a great difference on the content of phenolic compounds.Dihydrochalcone and flavonol have a relative stable content when treat with ethophen,but the content of phenolic acid,especially the content of chlorogenic acidin treat group is 30 times more than that of check group after the 4 days treatment,this result prove that ethophen can directly induce the synthesis of chlorogenic acid and the increase content may originated from a answering mechanism in such adverse condition.The research reveal that the content of dihydrchalcone is highest but the content of phenolic acid is lowest in the leave of Malus‘radiant',which preliminarily find the change rule of phenolic compounds in different development stages,these results can provide a theoretical guidance for apple breeding and artificial extraction of phenolic compounds.