Genetic Analysis of Native Silkworm, Nangnoi Si Sa Ket 1 Variety, by RAPD-PCR Technique

Abstract

Thai native silkworm (Bombyx  mori L.), Nangnoi Si Sa Ket 1, one of the certified varieties from Department of Agriculture, has been extensively distributed to others research stations in Thailand for sericulture promotion at farm level. Due to rapid multiplication rate, the genetically alteration and contamination within the variety presumably occurred. Accordingly, genetic analysis of native silkworm, Nangnoi variety based on Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) Technique was carried out to determine variation of this variety collected from various sericulture stations including Chiang Mai, Mukdahan, Nong Khai, Roi Et, Sakon Nakhon, Si Sa Ket, Ubon Ratchathani, and Udon Thani. Three native silkworm varieties including Kiewsakon, Nanglai, and Nangluang and also one wild silkworm (Samia ricini Boisduval) variety were selected and assigned as corresponding referenced band patterns. DNAs of those silkworms were extracted from haemolymph and 18 RAPD primers were applied to random amplification. RAPD products were spreaded on agarose gel-electrophoresis and polyacrylamide gel-electrophoresis to generate polymorphisms of DNA band pattern. RAPD primers OPO-07 and OPD-11 produced specific bands at 430 and 100 bp that specified Nangnoi Ubon obtained from Roi Et from others. Meanwhile, RAPD primer, OPN-02, also produced 2 specific bands. First band, 985 bp in size, differentiated between Nangnoi Si Sa Ket from Nong Khai from others and second band, 434 bp in size, separated Nangnoi  into 2 groups: Nangnoi Ubon and Nangnoi Si Sa Ket. The combined analysis of band pattern generated by all those 3 primers supported that Nangnoi Ubon and Nangnoi Si Sa Ket was genetically related and recently diverged from each other perhaps caused mainly by the screening process during mass rearing of Nangnoi Si Sa Ket 1 in various research stations.