| A total of more than60species of genus pear in the world, and there are13kinds originating in our country, the pear germplasm resources were rich in our country. China is one of primary center of pear domestication in the world, owning very abundant germplasm resources of pear, wild Pyrus ussuriensis Maxim. mainly distributes in Liaoning, Heilongjiang, Longxi and Hexi province. A sersis of study found the wild resource not only came into being wildly genetic divesity but also form the character of strong resistance in the process of coevolution with the environment and plant diseases and insect pests, and is the valuable gene bank for resistance and quality fruit breeding.Wild Pyrus ussuriensis is a specie with forte fortissimo cold resistance in Pyrus, and it’s fruits were sweet, delicious and have characteristics fragrance after-ripening, it is fruit be table winemaking and processed into other foods, having high medicinal value. researching of wild Pyrus ussuriensis resources protection strategy, system evaluating, and excavating and making use of excellent germplasm research can effectively enlarge the genetic basis of pear tree species, and have great significance in supporting the sustainable development of the pear industry in China. Although some domestic scholars research of wild Pyrus ussuriensis had carried in different levels, but the systematic researchs on the genetic diversity of wild Pyrus ussuriensis germplasm resources were not reported, therefore, so we investigated the genetic diversity of the germplasm resources from phenotypes and molecular phylogenetics, and to provide scientific basis for conservation and utilization of wild Pyrus ussuriensis germplasm.The main results are as follows:1. The percentage of polymorphic loci (P) was82.95%, Nei’s gene diversity (H) was0.1467and the Shannon information index (I)was0.2397at specie level which indicated the genetic diversity of wild Pyrus ussuriensis was low;2. The Dongning population had the richest genetic diversity with the highest polymorphic loci (P=74.94%), Nei’s gene diversity (H=0.1440) and Shannon information index (I=0.2384) in3populations and was preferential population in si-tu germplasm conservation strategies;3. The genetic differentiation coefficient between populations(GST=0.1008) showed that genetic variation in populations was the mainly source of wild Pyrus ussuriensis genetic variation. Gene flow (Nm) was4.4603indicated that there were frequent gene exchange between populations;4. The UPGMA cluster analysis showed that the3populations were Mendelian relative independent populations, and the closer genetic relationship existed between the Hailin and Dongning populations;5. There were wide ranges of genetic variation in fruit size, total content of volatile compounds, numbers of various and contents of volatile compounds, the segregation ratio and content of main volatile components, content of sugars and organic acids andcontent of total sugars and organic acids, the variation coefficient (CV) were more than17%. So there were significant difference among seedings. The wild Pyrus ussuriensis has the rich diversity in the morphological trait;6. The Vertical length, transverse length and weight of Wild Pyrus ussuriensis fruits were less than3cultivars, but fruit shape index is more close to the cultivars;7. Comparison with3cultivars, the kinds and content of volatile compounds of seedlings were higher than cultivars obviously. The seedings have acids and hydrocarbon derivates compounds,9class111kinds of unique elements (such as esters),8unique character impact odors, such as butanoic acid, hexyl este;8. The sugars and organic acids of the wild seedlings were identical with the cultivars, and contents of fructose and malic acid were all the highest in the seedlings and cultivars. The contents of tartaric acid and sucrose in the wild seedlings and the content of total sugars and organic acids in some wild seedlings were significantly higher than3cultivars... |
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