Technical Abstract: This blueberry project is funded in 2008-2011 by the Specialty Crops Research Initiative of the United States Department of Agriculture’s National Institute of Food and Agriculture. Our objectives are to develop genomic resources for blueberry, which include EST libraries, co-dominant molecular markers, and genetic linkage maps in diploid and tetraploid blueberries. We plan to use these markers to identify QTLs associated with cold hardiness, chilling requirement, and fruit quality traits, and in studies of genetic diversity, gene flow, and evolutionary relationships between wild blueberry species. In 2009, cDNAs were prepared from fruit at different stages of development, flower buds at different stages of cold acclimation, and leaves, to generate over 100,000 ESTs. Three hundred and seven out of 636 SSR primer pairs designed from previously available ESTs were screened for polymorphism in parents of the mapping populations and are being added to each map. Plants from the tetraploid mapping population were propagated and established at various locations. Plants from the diploid mapping population were evaluated for cold hardiness for the first year. In a study on gene flow in wild lowbush blueberry, two high- and two low-producing clones from each of two cultivated fields in Maine were used as pollen recipients in hand crosses. Mixtures of pollen from each clone’s neighborhood, as well as the other three neighborhoods in that field, were applied in crosses. Interestingly, the lowest producer’s yield (fruit set times mean berry weight) was increased by 2-6 times when pollinated by any of the three ‘foreign’ pollen neighborhoods as compared to their own neighborhood. A preliminary phylogenetic tree of Vaccinium species in section Cyanococcus was constructed based on length polymorphisms of EST-PCR markers.