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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #310633

Research Project: Evaluation and Genetic Improvement of Woody Ornamental Landscape Plants for Disease and Pest Tolerance, Non-Invasiveness, and Ornamental Traits

Location: Floral and Nursery Plants Research

Title: Development of polymorphic genic-SSR markers by cDNA library sequencing in boxwood, Buxus spp. (Buxaceae)

Author
item Thammina, Chandra - Rutgers University
item Olsen, Richard
item Wight-malapi, Martha
item Crouch, Joanne
item Pooler, Margaret

Submitted to: Applications in Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2014
Publication Date: 12/1/2014
Citation: Thammina, C., Olsen, R.T., Wight-Malapi, M., Crouch, J., Pooler, M.R. 2014. Development of polymorphic genic-SSR markers by cDNA library sequencing in boxwood, Buxus spp. (Buxaceae). Applications in Plant Sciences. 9(12):1400095.

Interpretive Summary: Boxwood (Buxus species) are popular woody landscape shrubs grown for their compact and varied forms and deer-resistant, broad-leaved evergreen foliage. Boxwood plants grown in temperate zones are increasingly threatened by a destructive new blight disease, caused by the fungus Calonectria pseudonaviculata. The disease has spread throughout continental Europe, parts of western Asia, and into the U.S. To date, all tested cultivated boxwood taxa are affected by boxwood blight, although some taxa appear to be more susceptible to the fungus than others. There is an urgent need to develop blight tolerant boxwood cultivars because of the economic impact this disease has on landscapes and commercial growers. The National Boxwood Collection at the U.S. National Arboretum (USNA) contains more than 700 Buxus accessions, making it one of the most complete collections in the world and a valuable genetic resource for developing blight-tolerant varieties. However, genetic relationships and diversity among these accessions have not been determined. We have developed the first genic-SSR markers for boxwood, which will be useful in characterizing genetic diversity and relatedness of boxwood germplasm to aid in our overall objective of developing blight tolerant varieties.

Technical Abstract: Genic microsatellites or simple sequence repeat (genic-SSR) markers were developed in boxwood (Buxus taxa) for genetic diversity analysis, identification of taxa, and to facilitate breeding. cDNA libraries were developed from mRNA extracted from leaves of Buxus sempervirens ‘Vardar Valley’ and sequenced using the Illumina MiSeq system. Approximately 11.9 million base pairs of sequence data were examined and 845 genic-SSRs were identified, including 469 dinucleotide, 360 trinucleotide, seven tetranucleotide, one pentanucleotide, and eight hexanucleotide repeats. Primer pairs were designed for 71 selectively chosen genic-SSRs containing trinucleotide repeat motifs and were used to amplify the corresponding loci in 18 diverse boxwood accessions. Twenty-three primer pairs amplified polymorphic loci, with two to nine alleles per locus. These novel polymorphic genic-SSR markers will aid in evaluating genetic diversity of boxwood germplasm and allow verification of hybrids and cultivars for breeding programs.