Molecular Markers Development And Genetic Relationship Anaysis Of Blueberry And Relative Species

Blueberry?Vaccinium spp.?belongs to the genus Vaccinium in family Ericaceae and cranberry?V.macrocarpon?is its relative species.They are widely cultivated in the world because of good tasty and abundant nutrition.Accurate and effective identification strategy is needed to develop to solve the increasing cultivar confusion.Different molecular markers,which aim at distinct genomic positions,show versatile loci polymorphism.So combination of different molecular markers is helpful to detect phylogenetic relationship and to identify germplasms,particularly for fruit trees that with narrow genetic background.In this study,SSR,SSAP and Chloroplast DNA,were developed to identify cultivars and to analyze phylogenetic relationships among blueberries and cranberries.The main results were as following:?1?SSR loci were searched and analyzed in the leaf transcriptomic sequence of 'Brigitta'.The frequency of SSR was 21.32%,accounting for 22058 SSR loci.The highest type of SSR motif was dinucleotides with the frequency of 77.70%,followed by trinucleotides with the frequency of 21.45%.A total of 15 pairs of core primers with clear and stable amplification bands were screened from 53 random pairs of primers.Genetic diversity of 52 accessions in genus of Vaccinium was estimated using the 15 core primers.The results showed that the maximum number of effective alleles was 5.883?VcSSR50?and the minimum value was 1.642?VcSSR20?,with an average value of 3.227.The average of Shannon diversity index was 1.193,ranging from0.490 to 1.870.The range of observed heterozygosity and expected heterozygosity were 0.024⁰.930 and 0.262⁰.866,with mean values of 0.603 and 0.628,respectively.It could be inferred that the genetic background of blueberry cultivars 'Legacy'origins from southern blueberry V.formosum while V.corymbosum contributed to the breeding process of rabbiteye blueberry 'Nobilis'.?2?After preliminary prediction and succedent screening,a total of 98070 bp long terminal repeat retrotransposon?LTR-RT?sequences were found,which accounted for 3.96%of the whole blueberry genome.1.58%Ty1/Copia retrotransposon family and 2.39%Ty3/Gypsy retrotransposon family were identified by the amount of 33 and 60 respectively.36 pairs of primers were screened from 78random pairs of primers.In this study,the average of each locus was 99.96%,with the range from 47 to 222.Although northern highbush blueberry 'Bluecrop'and 'Blueray'bred from the same parents,the genetic composition or genetic background of them was incompatible partly.Rabbiteye blueberry 'Bonita'resembles genetic composition with highbush blueberries.Combining the results of SSR and SSAP,it could be inferred that V.corymbosum possibly involved in rabbiteye blueberry breeding process.?3?28 variation sites and 8 haplotypes were detected at chloroplast DNA non-coding regions trnL^UAA-trnF^GAA,trnH^GUG-psbA,rpS12-rpL20 and trnL-trnF.The haplotype diversity?H_d?and nucleotide diversity???were 0.727 and 1.19×10^-3,respectively.The highest genetic diversity(H_d=0.727 and?=1.19×10^-3)was found in southern highbush blueberry cultivars.Seven and five haplotypes were detected in southern and northern highbush blueberry cultivars(H_d=0.727 and?=1.19×10^-3),respectively.There was one haplotype in rabbiteye blueberry cultivars and cranberry cultivars.?H_d=0 and?=0?.Haplotype H3,which shared by southern highbush,nouthern highbush and rabbiteye blueberry,was the most popular haplotype.Haplotype H1,H2,H4and H6 were detected in two different blueberry groups and haplotype H5 and H7 were exclusively detected in Ssouthern highbush blueberry cultivars.Meanwhile,haplotype H8 was unique to cranberry cultivars.The cpDNA haplotype network of blueberry and relative species suggested that the evolutionary process of blueberry is conservative and H3 was the ancestral cpDNA haplotype.