Evaluation On Germplasm Resources And Structure Of Core Germplasm Bank Of Sinkiang Pear(Pyrus L.)

Pear(Pyrus L.) belongs to Rosaceae, Maloideae,Pyrus L. It is primarily a deciduous fruit tree havingoriginated in the western hills of China. Distribution throughout the country has made the Pear famous inchina.On the basis of a preliminary investigation of Pear germplasm resources in XinJiang and observationsof botanical characteristics, we carried out a study on the external and internal quality of fruit and coldresistance. We conducted a survey of SRAP molecular markers and cluster analysis using a randomsampling cluster strategy method and the principle of priority selection with extreme individual expressionof resource clustering, compression step by step build of pear core germplasm bank.Through this article research would be discover the excellent genes and in order to grasp the botanycharacteristics, quality traits, hardiness of Pear Resources in XinJiang.This would provide a theoreticalbasis and genetic background information for long-term Preservation the Genetic Diversity and promotionof genetic improvement and lay a good foundation for genetic breeding and molecular breeding of Pyrus L.The main results were as follows:1. Research results of the part of Botany Characteristics the Pears(Pyrus L.)Pear tree canopy shapes include cone, broadly conical, round head, semicircle, spindle, oblate, narrowconical, cylindrical canopy shapes. The color of tree trunk may be gray, beige or dark brown. The color ofone year old branches may be brown, beige,yellow, green, dark gray, gray or celadon. Varieties ofP.sinkiangensis Yu and P.ussuriensis Maxim leaf edge has entire or a few serrate,while P.betulaefolia Bgehas corrugated serrate and the P.armeniacaefolia Yu has obtuse serrate. Most of the pear varieties hasserrated leaves and the color from green to dark green with leaf apex that is acute and sharp.Pear inflorescence ranges from5-18flowers, while the inflorescence of most varieties of pear hasbetween5-9blossoms. The varieties P.calleryana Decne. and P.betulaefolia Bge has13to18blossoms.The number of petals range between5-9, while most of the varieties has five petals. Results show that12.6%of varieties stigma position is lower than stamens and31.6%of varieties stigma position equal tostamens and55.8%of varieties stigma position is higher than stamens. Stamen number ranges between14and28,majority of varieties stamens number about18to22.Pear blossom buds begin at the end of March to early April. Pear tree blossoms begin to open on April8to April18. Full-blossom period is April13to21and the end of blossom period is on April30. Undernormal weather circumstances, each varieties period of bloom to fallen petal requires7-12days and leafgrowth later than blossom by1-3days. Pear fruit mature during the period at the end of July to lateOctober.2. Research results of evaluation fruit quality of Xinjiang cultivated PearsPear fruit appearance quality and inherent quality were determined with physiological indexes andranking through a “reasonable–satisfaction” value. Appearance quality indicators include fruit weight,fruit shape index, fruit stems, terminal depression, core size, hardness and fruit internal quality indexincluding soluble solids, juice, vitamin C, soluble sugar, total acidity, sugar acid ratio, stone cells and so on.Each pear fruit variety are different with appearance quality and internal quality index. There was a largevariation of total acidity, sugar acid ratio, stone cell index among different varieties. According to the result of the determination of physiological index data are appraised “reasonable–satisfaction”.Thesynthesis of Xinjiang cultivated pear varieties “reasonable–satisfaction” value is between0.210~0.818.According to the reasonable satisfaction synthesis, ranking is arranged with the top10high quality varietiesas follows: NanGuoli Pyrus> Sha03> Korla fragrant pear> WanXiu Pyrus> DangShan Pear> HuangJinli Pyrus> Xizilv Pyrus> AiWenQieke Pyrus> Sha01> Baodao Xinshiji Pyrus> XinGao Pyrus.3. Research results of evaluation analysis the average subordinate function values andcomprehensive evaluation method to pear cold-hardinessThe average subordinate function values and comprehensive evaluation method for each species andvarieties are evaluated. The cold-hardiness ability with the increase of average subordinate function valuesare stronger and on the contrary of decreasing. The average subordinate function values analysis gavevalues between0.351~0.560.According to the result of comprehensive evaluation judgment for coldresistance, the Cultivated varieties were Da Xiang Shui Pyrus, Bei Feng Li Pyrus, Nai xi Pu te Pyrus, KuChe Amute Pyrus, Xi Shui Pyrus,Bei Hai Dao Wang Pyrus, He se Juju Li Pyrus， Yining WanduxiaPyrus,YuanHuang. Pyrus,Huocheng Bayue LI Pyrus,Kete Amute Pyrus. Among the Rootstock varietiesof pear the strongest Rootstock varieties were S5Pyrus and Zhong Ai-1Pyrus.. In the high canopy shapesrootstock,the highest cold resistance varieties were P.betulaefolia Bge.4. Research results of SRAP molecular markers Analysis to genetic diversityThis study was carried out to establish the genetic diversity of95cultivars of XinJiang pears by theuse of a molecular marker technique called SRAP (Sequence related amplified polymorphism). Freecombination of168pairs of SRAP primers which included14pairs of primers with strong specificity,stability was analyzed. Altogether163bands were amplified from14Primers, among which there were160bands with polymorphic loci. The percentage of polymorphic bands in all primers was98.16%.The Pear Germplasm Resources of95cultivars of XinJiang the average allele frequency was (Pi)0.3919, effective number of alleles (Ae) was6.5101,Shannon’s diversity index (I) was0.5296. Thecoefficient of genetic similarity of95germplasm resources were between0.3620to0.8466. The SRAPgenetic relationship dendrogram cluster analysis showed that95pear germplasm based on the0.598geneticsimilarity coefficient is divided into two categories, first category group included37germplasm and thesecond category included58germplasm; The Nei genetic similarity coefficient at the0.604level, can bedivided into five subcategories.5. Representative and diversity of pear core germplasm repository build resultsCore collection must be representative of diversity and specificity. Core collection established by thegenetic diversity of the initial part of the germplasm resources. This study made use of the molecularmarker technique SRAP and multiple cluster groups method to build a pear core collection. The corecollection included28cultivars from P.bretschneideri Rehd.， P.sinkiangensis Yü.，P.phaeocarpa Rehd.，P.ussuriensis Maxim.， P.communis L.， P.armeniacaefolia Yu Hybrids， P.calleryana Decne.， P.serrulataRehder. and dwarfed interstocks.Core collection compared initial germplasm resources by T-test showed has not significant differenceat0.01level for the effective number of alleles and Nei’s genetic diversity as well as Shannon’s geneticdiversity index. Meanwhile, the core collection higher than keep Germplasm with the effective number ofalleles, Nei’s genetic diversity, Shannon’s genetic diversity index information. The genetic diversity of the28cultivars represented in the core collection was very representative for polymorphism in XinJiang Pears.