Preliminary Identification Of The Metabolites Related To Russet Peel In Sand Pear (Pyrus Pyrifolia Nakai)

Pear(Pyrus spp.)is one of the most important and widespread fruit trees in the world.At present,the basic reason for the formation of russet peel in sand pear fruit has been clear.But,the metabolites resulted from russet peel of sand pear are still unclear.Taken’Huanghua’ pear and its bud mutant ’Luhuanghua’as the research material and on the other hand bagging and unbagging treatments were carried out using metabonomics method to identify and compare different metabolites from the peel of mature fruit(Pyrus pyrifolia Nakai),some metabolites were identified which are preliminary involved in ’Huanghua’russet peel.Fllowed by,we identified and analyzed of the composition of wax and suberin of russet skin in ’Huanghua’ pear which provide an experimental basis to find the metabolites of russet from sand pear.The major results are as follow:1.Using metabonomics method to discover differential metabolites from the peel of mature fruit in ’Huanghua’ and its bud mutant ’Luhuanghua’.The data was analyzed using principal component analysis and partial least squares-discriminate analysis(PLS-DA).Differences of pear peel color resulted in the significant difference of metabolite.18 differential metabolites were found from GC-MS,mainly including organic acids(Oxalic acid,Malic acid,Citric acid),amino acids(Alanine,L-Asparagine)and sugars(D-Fructose,D-Glucose,Sucrose).43 differential metabolites were obtained from LC-MS,primarily including Fatty acids(Cis-15-tetracosenoic acid,5,9-tetracosadienoic acid,Linoleic acid,Linolenic Acid,Stearic acid,Docosanoic acid,Tetracosanoic acid),Esters(Dihexyl 1,2-benzenedicarboxylate,2-Monolinoleoylglycerol),triterpenoids(Ursolic acid,Squalene),Phenolics(5-O-trans-p-coumaroyl quinic acid,Vanillic acid,Chlorogenic Acid,Arbutin,),Flavonoids(Flavonoid),Phenylpropanoids(Coniferyl aldehyde,Cinnamic acid),sterols(Stigmasterol)and Vitamin E(δ-Tocotrienol,α-Tocotrienol).2.Taken ’Huanghua’ bagging and unbagging treatments as the material,using metabonomics method to find and compared the different metabolites from the peel of mature fruit.The data was analyzed using PCA and PLS-DA.Differences of pear treatments resulted in the significant difference of metabolite.16 differential metabolites were found from GC-MS,mainly including organic acids(Malic acid,Propanoic acid,Citric acid),amino acids(L-Aspartic acid,L-Asparagine)and sugars(D-Glucose,Sucrose,D-galactose).52 differential metabolites were obtained from LC-MS,primarily including Fatty acids(Docosadienoic acid,Docosanoic acid,18-Hydroxyoctadecenoic acid,Linoleic acid,Linolenic Acid),Esters(Methy cinnamate,Monostearoylglycerol,Monooleoyglycerol,Monolinoleoylglycerol),triterpenoids(Ursolic acid,Pomonic acid,Squalene),Phenylpropanoids(Caffeic acid,Cinnamyl alcohol,Hydroxycoumarin,Coumarin,Sinpyl alcohol),Phenolics(Arbutin,3,4-Dihydroxybenzoic acid,Hydroxyhydroquinone,Methyleugenol,P-Coumaric acid),Ketones(Benzy-heptnone),Hydrocarbon(a-Farnesene,Myrcene).3.To analyse the compositions of wax and suberin of russet skin in mature’Huanghua’ pear.The metabolites produced wax and suberin of perderm(phellem)of russet skin was evaluated qualitatively and relative quantitatively using gas chromatography-mass spectrometer(GC-MS).The results showed that the compositions of the wax from periderm consists of alkanes,alkanols,alkanoic acids,unsaturated fatty acids,glycerides,sterols,pentacyclic triterpene alcohol and terpenoids.Among these components,the content of hexadecanoic acid(13.834%),octadecanoic acid(9.486%),9-octadecenoic acid(6.706%)and 9,12-Octadecadienoic acid(4.797%),were the higher than the content of other components.The depolymerization products of suberin contained glycerol,phenolics,1-alkanols,1-alkanoic acids,saturated a,co-diacids,substituted α,ω-diacids,saturated co-hydroxyacids,2-hydroxyacids,substituted co-hydroxyacids,monoacylglycerols,unsaturated fatty acids and triterpene and so on.Among these components,the levels of glycerol(1.114%),3,4-dihydroxybenzoic acid(1.073%),ferulic acid(2.670%),hexadecanoic acid(11.842%),octadecanoic acid(8.618%),hexadecanedioic acid(2.628%),9,10-Dihydroxyoctadecanedioic acid(1.417%),16-Hydroxyhexadecanoic acid(2.066%)and 9,10,18-Trihydroxyoctadecanoic acid(5.792%),were the higher than that of other compounds.