ABSTRACT
Beauveria bassiana (B. bassiana) is a broad-spectrum entomopathogenic fungus that can control pests in agriculture and forestry. In this study, encoding ecdysteroid uridine diphosphate glucosyltransferase gene (egt) was successfully screened in B. bassiana on the medium containing 500µg/mL G418 sulfate solution through the protoplast transformation method. This enzyme has the function of 20E (20-hydroxyecdysone) inactivation, thus increasing the mortality of the early instar larvae infected with B. bassiana. In this study, we transformed B. bassiana with the egt gene, which deactivates 20-hydroxyecdysone, a key hormone in insect development. The results showed that transgenic B. bassiana killed more silkworms of the 2nd instar larvae than the wild-type with a shorter LT50 time, which was reduced by approximately 20% (day 1 of the 2nd instar silkworm infection of B. bassiana) and 26.4% (day 2 of the 2nd instar silkworm infection of B. bassiana) compared to the wild-type, and also showed a higher mortality number before molting. The transgenic B. bassiana had a higher coverage of the body surface of silkworms compared to the wild type on the 3rd instar. In summary, improving entomopathogenic fungi using biological methods such as genetic engineering is feasible.
ABSTRACT
Energy metabolism is a fundamental process in all organisms. During silkworm (Bombyx mori) embryonic development, there is a high demand for energy due to continuous cell proliferation and differentiation. Estrogen-related receptors (ERRs) are transcriptional regulatory factors that play crucial roles in mammalian energy storage and expenditure. Although most insects have one ERR gene, it also participates in the regulation of energy metabolism, including carbohydrate metabolism in Drosophila, Aphid, and Silkworm. However, no study has reported the direct impact of energy metabolism on embryonic development in silkworms. In this study, we used transgenic technology to increase silkworm (B. mori; Bm) BmERR expression during embryonic development and explored the impact of energy on embryonic development. We found no significant change in the quality of silkworm eggs compared to that of wild-type silkworms. However, there was an increase in the consumption of vitellin, a major nutrient in embryos. This resulted in a decrease in glucose content and a significant increase in ATP content. These findings provide evidence that the acceleration of energy metabolism promotes embryonic development and enhances the motility of hatched silkworms. In addition, these results provide a novel perspective on the relationship between energy metabolism and embryonic development in other insects.