| Phenotype observation, biochemistry analysis, and molecular biology identification can be used to identify the diversity of living beings. The author of his article evaluated the diversity of Pyrus germplasm in two aspects. One is to reveal the diversity of pear germplam resources by the codominant SSR markers using Chinese old sand pear accessions, and disclose the relationship among them and the cultivars of P. pyrifolia, P. ussuriensis, P. bretschneideri, P. communis, and Japanese P. pyrifolia accessions, and furthermore, explore the evolution of pear. Second is to analyze the composition and level of flavonoids, to find out the pear accessions with high level of flavonoids. Main results are as follow:1. Based on Fluorescence sequencing technology, nine SSR markers successfully produced 1 or 2 discrete amplified fragmens in all 106 accessions examined, and could be used to set up the fingerprints of pear accessions evaluated.2. For the 106 accessions of 4 species, the number of alleles per locus ranged from 11 to 23, with an average value of 16.3. The expected heterozygosity (He) ranged from 0.31, to 0.89, with a mean value of 0.78. The observed heterozygosity (Ho) ranged from 0.27 to 0.83, with an average value of 0.60. The polymorphic information content (PIC) ranged from 0.29 to 0.88, with an average value of 0.77. For the 87 Chinese P. pyrifolia accessions, the number of putative alleles per locus ranged from ten to 21, with an average of 15.3; the expected heterozygosity (He) ranged from 0.29 to 0.89, with a mean value of 0.77. The observed heterozygosity (Ho) ranged from 0.29 to 0.84, with an average value of 0.60. The polymorphic information content (PIC) ranged from 0.28 to 0.88, with an average value of 0.75.3. Based on the SSR data, the similarity of 106 accessions investigated in this study could be depicted in a UPGMA phenogram. The dendrogram revealed 2 major groups, corresponding to the European pears and Asian pears. Asian pears grouped together based on geographical origin. Four P. ussuriensis cultivars (’Balixiang’,’Jingbaili’, ’Manyuanxiang’, and ’Nanguoli’) grouped together, and showed distant relationship with the cultivars of P. pyrifolia. The P.bretschneideri cultivars evaluated in this article dispersed in different P. pyrifolia groups.’Pingguoli’ and ’Qiubai’, which originated in Northeast China, showed close relationship with accessions of northern group P. pyrifolia; ’Chili’,’Dangshansu’, and’Yali’, which originated in the Yellow River Basin and the North China Plain, showed close relationship with some P. pyrifolia cultivars of Yellow River and Huai River group. It showed that, at least some P. bretschneideri cultivars are genetic related with P. pyrifolia cultivars. Japanese P. pyrifolia cultivars evaluated in this article showed close relationship with some Chinese P. pyrifolia accessions in Zhejiang, Jiangxi, and Yunnan province. The similarity coefficients of ’Xiaomeili’ from Zhejiang province with’Housui’,’Choujuurou’, and Shinseiki were 0.75,0.72, and 0.69, respectively; the similarity coefficients of’Jiangwantangli’from Jiangxi province with ’Housui’,’Choujuurou’, and Shinseiki were 0.62,0.80, and 0.77, respectively.4. TP-M13-SSR automated fluorescent detection system is economic, sensitive, and effective, especially suitable for the genetic diversity analysis of some pear accessions by a large number of SSR markers.5. Variation of total flavonoid levels in fruits of 186 pear accessions was determined by spectrophotometric method. The results showed that the total flavonoid levels in fruits of Pyrus germplasm resources ranged from 188.6 mg·kg-1 to 6773.0 mg·kg-1, with an average value of 825.7 mg-kg’1. The levels of total flavonoid in fruits of wild pear accessions were much higher than those in cultivated pear accessions.6. Arbutin, epicatechin, procyanidin B1, quercetin glucoside, procyanidin B2, procyanidin C1, quercetin rutinoside, catechin, quercetin galactoside, and quercetin arabinoside were detected among the fruits of 186 pear accessions analyzed by high performance liquid chromatography (HPLC), with the average values of 1264.81 mg·kg-1, 24.80 mg·kg-1,23.38 mg·kg-1,18.47 mg·kg-1,15.19 mg·kg-1,15.07 mg·kg-1,5.35 mg·kg-1, 2.61 mg·kg-1,2.04 mg·kg-1, and 0.24 mg·kg-1 respectively. Phloridzin, quercetin, quercetin peltatoside, quercetin xyloside, quercetin rhamnoside, cyanidin galactoside, cyanidin arabinoside, and cyanidin glucoside, were undetected.7. Ten pear accessions with higher flavonoid levels were found, they are ’P. ussuriensis -Neimeng’,’P. calleryana’ ’P. betuleafolia -Zanhuang’,’P. betuleafolia -Lingwu’,’Jianbali’,’Huagaili’,’Dongmi’,’Hongnahe’,’Daxiangshui’ and ’Huangxianchangba’.’P. ussuriensis-Neimeng’is a special pear germplasm with higher level of epicatechin, catechin, procyanidin B2, procyanidin C1, quercetin rutinoside, and arbutin;’Huagaili’ is rich of epicatechin, catechin, procyanidin B2, procyanidin C1, and quercetin glucoside. |
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