EC Veterinary Science

The mulberry silkworm (Bombyx mori L.) is a species of great economic importance. Currently, there is a great variety of breeds, which is related to their different origins, as well as the selective activities carried out in different breeding centers around the world. Various methods have been used to assess genetic diversity in this species. One of them is the method of polyacrylamide gel electrophoresis (PAGE), which is used in the present work.

This study aimed to evaluate the degree of genetic variability and phylogenetic relationships between thirteen breeds of mulberry silkworm (Bombyx mori L.) from genetic resources of Bulgaria through isozyme polymorphism. PAGE was used. Among nine studied isoenzyme loci, by eight loci (Bes A, Bes B, Bes D, Bes E, Pgm A, Mdh A, Bph and Alp A) was found intra-breed and inter-breed polymorphism. At the Hk locus, we found inter-breed polymorphism only. The number of alleles per polymorphic locus ranged from one to two. The degree of polymorphism ranged from 0% to 77.80%. Low levels of observed heterozygosity in comparison with the expected one have been calculated in all of breeds. The combined F_IS value over all polymorphic loci was 0.3205, which reflects a substantial deficit of heterozygotes. The value of F_ST showed that 49.21% of the overall genetic diversity observed was among breeds. The dendrogram constructed manifested that the two breeds of Japanese origin (Daizo and Japanese 106) were genetically most distant from other breeds. The data for isoenzyme polymorphism and genetic structure of the tested breeds can be used for genetic improvement and to develop new hybrids for silk production.

Keywords: Bombyx mori; Isoenzyme Polymorphism; Phylogenetic Relationships

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