An Economical Molecular Tool for Genetic Identity Confirmation in Blueberry

Cultivated blueberries (Vaccinium L. section Cyanococcus), originally derived from native North American species during the past century, have become a major global fruit crop. Significant production areas now can be found in North America, South America, Europe, China, Japan, Australia, and New Zealand. The United States Department of Agriculture (USDA) National Clonal Germplasm Repository (NCGR) in Corvallis, OR, is responsible for preserving genetic diversity of this important genus and its crop wild relatives, and maintains a national collection of 1689 accessions representing 91 species from 39 countries. Trueness-to type of the blueberry plants in this collection must be ensured for scientific, commercial and public needs. Use of an economical genetic fingerprinting set can assist in the reduction of clonal redundancy or elimination of inaccuracies for efficient conservation. The objective of this study was to develop an efficient and economical fingerprinting set that consists of reliable primer pairs that can be multiplexed in a single PCR reaction and differentiate genetic variants. Seventeen microsatellite, or simple sequence repeat (SSR) primer pairs, flanking core tandem repeats of three nucleotides were screened for polymorphism and ease of scoring in seven diverse blueberry cultivars. Five of these 17 primer pairs were selected to compose a single multiplex set and were evaluated in 287 blueberry plants preserved at the NCGR. The blueberries selected for evaluation were chosen based on the largest numbers of requests mostly from the scientific community. Two to four replicate plants with the same name were included in the study and represented a total of 126 accessions.  Eight accessions represented by a single plant were also included. One of the individuals from a set of five accessions with the same name had a unique genetic profile. Six pairs of accessions that had different names had identical SSR-based fingerprints. Additional SSRs will determine if the identical fingerprints of differently named cultivars is the result of low discriminating power of the fingerprinting set or by plant misidentification.