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Citrus as one of the important species of fruit trees in the world , has an important production and research value . However, due to the the citrus species between easy hybrid the bud mutation frequency and long history of cultivation , the genetic relationship between citrus species complex classification system has not yet been decided . Development and use of molecular markers polymorphism evaluation of citrus fruit trees , it is possible to provide solutions for problems ways . Single nucleotide polymorphism is caused by a single base variation of DNA sequence polymorphism , is the third generation of genetic markers . Single nucleotide mutations multi- position , high frequency , good stability , suitable for large-scale analysis . Development and utilization of a single nucleotide polymorphism molecular markers , polymorphism evaluation of citrus germplasm resources , you can explore the classification of the evolutionary relationships between the citrus species , but also for gene mapping and integration mapping can also study gene function , molecular marker-assisted breeding . Thus , single nucleotide polymorphism markers for genetic and breeding of citrus has important theoretical and practical value and broad application prospects . In this paper , the case of a plant for materials , screening by PCR-SSCP analysis of SNP molecular markers the screened primers polymorphic PCR products from 84 pairs of primers , 18 pairs of 38 citrus and its related and 10 pairs of primers , PCR products were cloned and sequenced , and a total of 157 SNP loci , including a 14 - bp InDel sites , these sites are mostly second allelism only six SNP loci third class sex . Bands of PCR-SSCP genotyping, sequencing results of the cluster analysis , the results show that the true citrus fruit trees can be divided into five major groups , the first class is the trifoliate and dragon trifoliate , the second category refers Australia lemon , Yichang orange and turpinia lemon to lemon , citron and grapefruit , the fifth category of sweet orange , wide leather citrus, the hybrid citrus and kumquat, this result with previous The study is basically the same . The results also show that the use of a small number of different SNP combination possible to separate most of the samples, can be used for the identification of citrus hybrids and cultivars . Conclusion: The use of PCR-SSCP citrus SNP Research results show that the method can efficiently display citrus SNP polymorphism analysis results are reliable , and easy and cheap . SNP after all, a huge application potential of new molecular markers .
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