Study On Accessment Resources Of Different Blueberry Germplasm

Blueberry belongs to the genus Vaccinium in family Ericaceae.There are abundant plants belong to genus Vaccinium in China.However,study on genetic diversity and water stress resistance of blueberry were relatively rare in China.In the present study,genetic relationship of 46 blueberry germplasm was assessed using retrotransposon-based insertion polymorphism(RBIP)molecular marker.Agronomic traits of 20 blueberry germplasm was detected using botanical characteristics.Chromosome ploidy of 25 blueberry cultivars and 1 wild species was identified by flow cytometry.In addition,water stress resistance of different cultivars was estimated.We aimed at utilizing wild plants from Vaccinium and screening blueberry cultivars that are suitable to special climate of southern China.The main results were as following:(1)Using 45 blueberry cultivars and 1 cranberry germplasm,17 pairs of polymorphic primers were screened and LTR-RT based insertion polymorphism(RBIP)system of blueberry was established.Phylogenetic analyses and molecular identity of 46 germplasms were performed using RBIP markers.The locus in which the highest polymorphism is Vmrgl,the lowest locus is Vmrg14.The size of PCR products varied from 200 to 463 bp,and the minimum and maximum length products were found at loci Vmrc3 and Vmrc19,respectively.All the germplasms were clustered into 6 groups in the phylogenetic tree.Group I was comprised of 3 northern highbush blueberries while cranberry was clustered into groups VI.Other four groups included northern highbush blueberries,southern highbush blueberries and rabbit blueberries.Molecular identity of 45 blueberry and 1 cranberry germplasms were constructed using "1" and "0" strings obtained from 17 polymorphic loci,which provided references for identification,verification and conservation of blueberry germplasms.(2)Correlation analysis,principal component analysis(PCA)and cluster analysis were performed to investigate the relationship among different blueberry germplasms.The correlation analysis showed that significantly positive correlations were observed(P＜0.01)between style length and flower longitude diameter,fruit weight and fruit width and fruit length,fruit calyx wide and fruit weight and fruit width,soluble solid content and fruit hardness.Significant difference(P<0.05)appared between fruit width and fruit calyx wide.The principal components analysis showed that the cumulative contribution of variance of the first four traits principal components accounted for 83.92%,the first one reflected leaf and fruit characters,the second reflected flower character,the third effected leaf characters.The clustering results showed that all the germplasms were clustered into 4 groups in the phylogenetic tree.Two southern highbush blueberry germplasms ’Emerald’ and ’Bluerain’ were clusted into one group and other group included both northern highbush blueberry and southern highbush blueberry.(3)Chromosome ploidy of 26 blueberry germplasm was identified by flow cytometry.All the germplasms showed 3 different ploidys,diploid,tetraploid and hexaploid,respectively.Four southern highbush blueberries,2 northern highbush blueberries,2 rabbit blueberries and Vaccinium duclouxii were diploid.Tetraploid cultivare included 7 northern highbush blueberries,7 southern highbush blueberries and 2 rabbit blueberries.Hexaploid was exclusively found in rabbiteye blueberry.(4)Physiological characteristics of different blueberry germplasm were investigated under water stress conditions.Drought treatment on blueberry showed that relative electric conductivity was increased and Chlorophyll was decreased with the stress intensity.’Cara’s Choice’ showed the highest tolerance in drought stress.The waterlogging stress results showed that Chlorophyll of 6 germplasm resource was declined with waterlogging stress prolonged,there was a little change of relative electric conductivity with the longer processing time.Comprehensive comparison result showed that drought inhibition growth of blueberry,but there is almost no effect on physiological change during waterlogging for blueberry.