Construction of a genetic linkage map of an interspecific diploid blueberry population and identification of QTL for chilling requirement and cold hardiness

A genetic linkage map has been constructed from an interspecific diploid blueberry population [(Vaccinium darrowii Fla4B × Vaccinium corymbosum W85-20) F₁#10 × V. corymbosum W85-23] designed to segregate for cold hardiness and chilling requirement. The map is comprised of 12 linkage groups (equivalent to the haploid chromosome number of diploid blueberry) and totals 1,740 cM. Included on the map are 265 markers based on simple sequence repeats, expressed sequence tag-polymerase chain reactions, single nucleotide polymorphisms, and randomly amplified polymorphic DNAs. The estimated map coverage is 89.9 %, and the average distance between markers is 7.2 cM. The mapping population was evaluated for 2 years (2009 and 2010) for mid-winter bud cold hardiness and for 3 years (2011–2013) for chilling requirement under controlled conditions. Broad-sense heritability of both cold hardiness and chilling requirement was quite high under these conditions with values of 0.88 and 0.86, respectively. One quantitative trait locus/loci (QTL) for cold hardiness and one for chilling requirement were identified that were consistent over at least 2 years. A second weaker QTL for chilling requirement was detected in only one of the 3 years.