Linkage and QTL Analysis of a Tetraploid Interspecific Pseudo-backcross Between Vaccinium corymbosum and V. arboreum

Vaccinium arboreum (Va), commonly known as sparkleberry, is a wild blueberry native from southeastern North America that is well adapted to sandy soils and often has a tree-like growth habit. Our objective was to construct a linkage map and perform the phenotypic characterization necessary for QTL analysis using an interspecific pseudo-backcross population between Vaccinium corymbosum (Vc) and Va.  Twenty-five vegetative and reproductive traits were evaluated for two seasons on 100 individuals obtained from the cross between the Vc cultivar Southern Belle (southern highbush) and the selection FL08-467. ‘FL08-467’ is an interspecific hybrid resulting from a cross between ‘Primadonna’ (Vc, southern highbush) and the selection ‘FL06-753’, a Va selection resulting from colchicine chromosome doubling. To build the tetraploid linkage map, two types of markers were used: simple sequence repeat (SSR) and single nucleotide polymorphism (SNP). A total of 352 SSR markers identified from genomic and EST libraries were tested for amplification and segregation, and a single PstI restriction enzyme digestion of genomic DNA of all progeny pooled for genotyping by sequencing resulted in 2553 SNP markers. TetraploidMap software was used to build the linkage map as well as to perform the QTL analysis. Twelve linkage groups were identified covering a total of 1401 cM. A total of 386 markers were placed on the resulting linkage map with an average distance between markers of 3.6 cM. QTL analysis was performed using trait data averages per season by year, and regions of interest for both plant architecture and reproductive traits were identified.