Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2011
Publication Date: 9/1/2011
Publication URL: http://handle.nal.usda.gov/10113/53781
Citation: Perera, O.P., Blanco, C.A., Ballard, L., Silva-Brandao, K.L., Domingues, F.A., Abel, C.A. 2011. Evaluation of anonymous and expressed sequence tag derived polymorphic microsatellite markers in the tobacco budworm Heliothis virescens (Lepidoptera: noctuidae). Southwestern Entomologist. 36(3):287-294. Interpretive Summary: Genetic markers suitable for population studies of the tobacco budworm, Heliothis virescens, were developed by evaluating variable markers isolated from unknown genomic regions and expressed genes. Fifteen genetic markers were validated after screening 147 nucleotide sequences from unknown genomic regions (anonymous markers) and 280 expressed gene sequences (EST markers), representing approximately 4% of the initial number of genetic markers identified. This low validation rate underlines the challenges in developing polymorphic genetic markers suitable for population studies in Lepidoptera. Ten of the validated markers were determined suitable for genetic studies of the bollworm, Helicoverpa zea.
Technical Abstract: Polymorphic genetic markers were identified and characterized using a partial genomic library of Heliothis virescens enriched for simple sequence repeats (SSR) and nucleotide sequences of expressed sequence tags (EST). Nucleotide sequences of 192 clones from the partial genomic library yielded 147 unique SSRs while EST screening identified 280 SSR containing sequences. All anonymous SSRs and 192 EST-SSRs were screened to select loci that produced best quality peaks without stutter peaks. Six anonymous markers and nine EST-derived markers were selected to evaluate a sample of 96 insects collected from Stoneville, MS, USA. The observed number of alleles ranged from 2 to 8 with an average of 5.87 (SE±0.53). The polymorphic Information Content (PIC) value averaged 0.446 (SE±0.052). Significant deviations from Hardy-Weinberg expectations were detected at 8 loci. We speculate that these loci are under selection in the population of tobacco budworm used in the study. No significant linkage disequilibrium was detected at any of the loci. Proportions of anonymous and EST-SSR markers validated after extensive screening were 4.08 and 4.68%, respectively. One anonymous SSR marker (HvMS117) and all nine EST markers were transferable to Helicoverpa zea.