暗化型家蚕(mln)对家蚕核型多角体病毒抗性的初步研究

Preliminary study on resistance of silkworm melanism mutant(mln)to nucleopolyhedrovirus of silkworm

通过对暗化型近等位基因系514mln、514家蚕幼虫添食BmNPV病毒悬浮液开展抗性试验,测定2品系的半致死浓度(LC_(50))、黑色素代谢通路多巴胺上、下游的基因(BmDDC,BmiAANAT,BmEboy)和家蚕抗BmNPV基因(Bmlipase-1、Bm-serine protease-2)的表达量变化以及家蚕幼虫头部内合成黑色素的前体物质多巴、多巴胺的含量变化,探析暗化型家蚕对BmNPV的抗性及其发生原因。结果显示:与野生型家蚕514相比,暗化型突变家蚕514mln 5龄幼虫LC_(50)明显提高;未添毒条件下514mln幼虫体内Bmlipase-1、Bm-serine protease-2的表达量显著高于514幼虫;在添毒条件下,514mln、514幼虫体内前述基因的表达水平均有提高,幼虫头部多巴、多巴胺的含量也均有明显增加。推测暗化型家蚕(mln)可以通过调高体内抗BmNPV基因表达量的形式来提高对家蚕BmNPV的抗性。

Resistance tests were conducted on the melanism mutant near Iso-genic linesc 514 mln and the silkworm 514 by feeding their larvae with a suspension of BmNPV virus.The half-lethal concentration(LC 50)of the two strains was determined,along with the expression levels of genes involved in the melanin metabolic pathway(BmDDC,BmAANAT,BmEboy)and the silkworm resistance genes against BmNPV(Bmlipase-1,Bm-serine protease-2).Additionally,the changes in the content of dopamine and its precursor,L-DOPA,synthesized in the heads of the silkworm larvae were investigated to assess the resistance of the melanism mutant silkworm to BmNPV and to explore the underlying mechanisms.The results indicated that the LC50 of the fifth instar larvae of the melanism mutant silkworm 514 mln was significantly higher compared to the silkworm 514.Under non-infection conditions,the expression levels of Bmlipase-1 and Bm-serine protease-2 in the 514 mln larvae were significantly greater than those in the 514 larvae.Under infection conditions,the expression levels of the aforementioned genes increased in both 514 mln and 514 larvae,and the content of L-DOPA and dopamine in the heads of the larvae also showed significant increases.It is inferred that the melanism mutant silkworm(mln)may enhance its resistance to BmNPV by upregulating the expression of its internal resistance genes.