2011 Annual Report 1a.Objectives (from AD-416) The overall research goal is to identify QTL associated with chilling requirement, cold tolerance, and various fruit quality traits in the tetraploid highbush blueberry (V. corymbosum) mapping population developed by Michigan State University. 1b.Approach (from AD-416) A tetraploid highbush blueberry (V. corymbosum) mapping population, derived from a cross between the northern highbush cultivar ‘Draper’ and the southern highbush cultivar ‘Jewel’, will be used for identifying QTL associated with chilling requirement, cold tolerance, and various fruit quality traits. The population will be propagated, planted, and evaluated for these traits at various locations, including Florida, Georgia, Oregon, and Michigan, over two years. EST-SSR and EST-PCR markers will be developed from blueberry ESTs and added to the current map of this population. QTL associated with chilling requirement, cold tolerance, and various fruit quality traits will be identified using appropriate software designed for mapping quantitative traits in tetraploid populations. 3.Progress Report The purpose of this agreement is to distribute part of the funds from a CSREES-funded Specialty Crop Research Initiative (SCRI) project entitled “Generating Genomic Tools for Blueberry Improvement” to the Co-PI at Michigan State University. Genomic resources for genetic improvement are lacking in blueberry. The objectives of this project are to add molecular markers to a genetic linkage map of blueberry and identify markers in this breeding population associated with cold hardiness, chilling requirement, and various fruit quality traits. This also relates directly to the parent project goal of enhancing blueberry performance through molecular approaches. Previously, leaf tissue was collected for DNA extractions, DNA was distributed to the various scientists on the project, and molecular markers were followed in the population for map construction. The tetraploid mapping population was asexually propagated and planted at five locations with varying winter temperatures and chilling hours: Gainesville, FL, Waycross, GA, Invergowrie, Scotland, Corvallis, OR, and Benton Harbor, MI. Plants at the various field locations are now being evaluated (in 2011) for many traits including timing of flower and leaf bud break, extent of vegetative development, timing of bloom, fruit color, fruit firmness, soluble solids, titratable acidity, yield, and total anthocyanins, among others. Potted plants of the mapping population were also evaluated for chilling requirement over one year. They were held in an unheated greenhouse in the winter of 2010-2011 and transferred to a heated greenhouse after the plants had received 250, 350, 450, 550, 650, 750, and 850 chilling hours. The genotypes showed a wide range in chilling requirements based on evaluations of their degree of floral and vegetative development. This research will be used by blueberry breeders to develop new, improved blueberry varieties through marker-assisted selection. Progress was monitored by the ADODR through numerous phone calls/conference calls and e-mails to exchange data and discuss research plans.