Microsatellite analysis of the silkworm strains (Bombyx mori): high variability and potential markers for strain identification

Abstract

The silkworm (Bombyx mori) is of great economic value from an industrial perspective. Casual discrimination and accumulation of genetic information from a diverse variety of silkworms are essential for practical utilization and long-term conservation. In this study, a total of 54 silkworm strains preserved in Korea were typed for nine polymorphic microsatellite loci. We determined per-locus numbers of alleles ranging from 3 to 17 with an average value of 7.5, per-locus observed heterozygosity ranging from 0.04 to 0.98, and per-locus polymorphic information content (PIC) ranging from 0.06 to 0.86, thereby indicating that some of these loci are profoundly variable. Phylogenetic analysis using the nine concatenated microsatellite loci showed no clustering on the basis of known strain characteristics and origin. A total of 17 strain-specific apomorphic alleles, which discriminate 14 among 54 silkworm strains, were obtained from eight loci. These strain-specific alleles can, therefore, be casually utilized to discriminate between applicable strains, without any further typing of other loci. Furthermore, a substantial number of homozygote strains, represented by 24 among 67 alleles in nine loci, were also detected. These results collectively implicate silkworm microsatellite DNA as useful and potentially important molecular markers for the eventual discrimination of silkworm strains, hundreds of which are currently preserved in Korea.

Microsatellite Analysis of the Silkworm Strains (Bombyx mori) Originated from China

“…Due by these merits microsatellite DNA has been used in many organisms for a diverse purpose (Edwards et al, 1991;Morgante and Olivieri, 1993;Dallas et al, 1995;Viard et al, 1996;Mariat et al, 1996;Pope et al, 1996;Romero et al, 2003). In the silkworm, abundant microsatellite primers have been published by several authors (e.g., Dharma Prasad et al, 2005), but only some of the Chinese strains kept in Korea were genotyped using microsatellite DNA (Kim et al, 2010).…”

Microsatellite Analysis of Silkworm Strains (Bombyx mori) of Japan Origin Preserved in Korea

“…The previous analysis of strains from China reported PIC values ranging from 0.34 to 0.82, with an average of 0.54 per locus (Kim et al, 2012). Furthermore, Kim et al (2010) reported that 54 silkworm strains originating from several countries exhibited a mean PIC value of 0.47 over all loci (nine loci, including the eight loci used in this study). The PIC values at each locus ranged from 0.06 to 0.86, which is slightly higher than the values we calculated for the strains from Japan.…”

“…Previous studies of silkworm strains originating from China also support this notion (Kim et al, 2010(Kim et al, , 2012.…”

“…Previously, Kim et al (2010) genotyped 54 silkworm strains preserved in Korea using nine polymorphic microsatellite loci, and described the importance of these markers for strain discrimination.…”

“…In this study, we selected eight microsatellite markers that were used in previous studies (Kim et al, 2010;2012), and genotyped 78 silkworm strains of Japanese origin that were preserved in Korea. The goal of this investigation was to determine the utility of the markers in detecting DNA polymorphism, and to assess their potential for use in strain discrimination.…”