Metabolic Proifling Analysis On The Main Quality Characteristic Components In A Natural Mutation Of Pear (Pyrus Bretschneideri Rehd. Cv. Dangshansuli) Fruits

Fruits contain a lot of sugar, acid and other nutrients with a unique aroma. The ratio ofsugar and acid has an obvious effect on the taste of fruit. Amino acids participate in thesynthesis of other quality characteristic ingredients in fruit, and also have a certainnutritional value. Aromatic substances in different fruits are different in thousand ways sothe flavor of each is distinct. The main quality characteristics are interlinked andtransformed into relative metabolic network which composes into the metabolic flow offruits. The fruit quality applications of the Metabolomics technology can not only revealthe formation, transformation and the essential interrelationship of sugar, acid, amino acids,aromatic matter, but also indicate the forming mechanism of the fruit quality, to improvethe fruit quality and control the quality under the modern biological technology.Pyrus bretschneideri Rehd. cv. Dangshansuli fruits which lied between Pyrusbretschneideri and Pyrus pyrifolia. in horticultural classification, has a long cultivationhistory with the largest cultivation area in DangShan county, Anhui province, China. P.bretschneideri ‘Dangshansuli’ is a Rosaceae woody fruit tree which is formed in sorbitolstuffs as the main photosynthesis production. At the same time, the fruit qualitycomposition, characteristics and formation mechanism are different from otherhorticultural crops.In recent years, there was a naturally mutation with high-content sugar in pear fruitswhich were found from germplasm resources of P. bretschneideri ‘Dangshansuli’. P.bretschneideri ‘Dangshansuli’ was used as the experimental materials in this paper. Theorganic phase extract and aqueous phase extract from the mature pear fruits and itshigh-content sugar counterpart (HCSC) were prepared, and metabolic profiling analysis onthe important fruit quality characteristic components of sugar and other metabolites relatedto sugar metabolism, including organic acids, amino acids and aromatic counpounds.GC-MS analysis technique combined with NIST and Wiley databases, the chemicalstructures of the metabolites were identified on the basis of MS spectrum data. HPLCcoupled with fluorescence detection was used to investigate the changes of the main aminoacid components in mature ‘Dangshansuli’ pear fruits and HCSC pear fruits. Thecomparable results of the main quality composition differences in ‘Dangshansuli’ pearfruits and HCSC pear fruits will be helpful to clarify the physiological mechanism ofabnormal sugar accumulation in HCSC pear fruits. The main results are showed as follows:In the organic phase extract of ‘Dangshansuli’ pear fruits and HCSC pear fruits,111 metabolites were identified.5-Ethyl-2-methyl-octane, tetradecane,1-hexacosanol,n-octadecane, dodecenylsuccinic anhydride, heptanoyl anhydride, n-hexadecanoic acid,1-hexadecanol,2-nonadecanone bis(2-ethylhexyl) phthalate, n-hexadecanal octadecanal,γ-sitosterol and lupeol were all present at significantly high levels in both pear fruitsamples. PCA analysis on the metabolite profiles of the organic phase extract gave a clearcluster pattern between ‘Dangshansuli’ pear fruits and HCSC pear fruits. A broad range ofmetabolites were found to influence cluster formation of organic phase metabolite profiles.The highly-associated metabolites extracted from the HCSC pear fruits were much morethan those of’Dangshansuli’ pear fruits based on their metabolic network analysis.In the aqueous extract of ‘Dangshansuli’ pear fruits and HCSC pear fruits,87metabolites were identified. Fructose, glucose, sucrose, glucitol, xylitol, palatinose, malic acid,hexanoic acid, L-proline and inositol were all present at significantly high levels in both pearfruit samples. The metabolic network analysis shows that the highly-associated metabolitesextracted from HCSC pear fruits were much more than those of’Damgshansuli’ pearfruits.HPLC coupled with fluorescence detection was used to investigate the differences ofthe main amino acid components between ‘Dangshansuli’ pear fruits and HCSC pear fruits.The amino acid components in pear fruit samples can be well separated. The results showthat there is a significant difference in the amino acid contents between ‘Dangshansuli’pear fruits and HCSC pear fruits. The contents of glutamic acid and cystine in HCSC pearfruits are125%and50%those of’Dangshansuli’ pear fruits, respectively. And thecontents of alanine and proline are1.51and2.29folds those of ‘Dangshansuli’ pear fruits,respectively.