Method for rapid distinction of Bombyx mandarina (Japan) from B. mandarina (China) based on rDNA sequence differences

The EcoRI site is located between the 5.8S and 28S rRNA genes in Bombyx mandarina (Japan) (Japanese type rDNA) but is absent in the rDNA of B. mandarina (China)(B. mori type rDNA) including the domesticated B. mori. Digestion of PCR products amplified by primers of both flanking sides of this EcoRI site with EcoRI should only be successful for amplification products of B. mandarina (Japan) containing Japanese type rDNA. The distribution of Japanese type rDNA in Japan, Korea, and China was determined using this rapid detection method. Japanese type was not detected in China or in Korea despite having 27 chromosomes. These findings suggest that the choromosome fusion and the rDNA type separation were independent evolutionary events. Invasion of B. mori chromosome #11 into Japanese B. mandarina (Japan) was examined.