中文摘要：

在室内选用Cry1Ac对小菜蛾Plutella xylostella 3龄幼虫进行抗性选育,获得相对抗性为356倍的抗性种群DBM1Ac-R品系。应用实时定量基因扩增荧光检测（real time quantitative PCR,real-time qPCR）技术检测敏感小菜蛾DBM1Ac-S和抗性小菜蛾DBM1Ac-R品系鞘糖脂（Glycosphingolipids,GSLs）合成酶基因bre-3和bre-5 mRNA在2龄、3龄、4龄和老熟幼虫、蛹及4龄中肠的表达情况。结果显示：bre-3和bre-5在两个品系的5个时期和4龄中肠均有表达,其中DBM1Ac-S品系的bre-3 mRNA在3龄、4龄和老熟幼虫的相对表达量显著高于DBM1Ac-R品系（P〈0.05）,分别为DBM1Ac-R品系的2.36、5.54和2.68倍;DBM1Ac-S品系的bre-5 mRNA在2龄至蛹期的相对表达量分别为DBM1Ac-R品系的1.19、3.13、1.78、1.75和1.65倍,其中由3龄到蛹期差异显著（P〈0.05）。DBM1Ac-R品系3龄至老熟幼虫的bre-3和bre-5 mRNA相对表达量降低可能与小菜蛾长期的Cry1Ac汰选有一定的关系。比较同一种群、同一龄期（包括4龄中肠）的bre-3和bre-5 mRNA相对表达量差异时,发现bre-5相对表达量均高于bre-3。研究结果为苏云金芽孢杆菌（Bacillus thuringiensis,Bt）杀虫晶体蛋白受体之一GSLs的进一步研究提供了一定的基础。

英文摘要：

DBM1Ac-R strain of Plutella xylostella was selected with Cry1Ac in laboratory and showed 356-fold resistance to Cry1Ac compared with a susceptible strain（DBM1Ac-S）.The relative expression of synthetase gene of Glycosphingolipid（GSLs） bre-3 and bre-5 mRNA of DBM1Ac-S and DBM1Ac-R strains were determined using real-time qPCR,from 2nd-instar to mature larvae,pupa and midgut of 4th-instar.The results showed that both bre-3 and bre-5 mRNA were found to express in different development stages and midgut;The relative expression of bre-3 mRNA in DBM1Ac-S strain was significant higher than DBM1Ac-R strain,exhibiting 2.36,5.54 and 2.68 times in 3th-instar,4th-instar and mature larvae respectively;The relative expression of bre-5 mRNA in DBM1Ac-S strain were 1.19,3.13,1.78,1.75 and 1.65 times respectively compared with DBM1Ac-R strain from 2th-instar to mature larvae.The results suggested that there may be a correlation between the lower relative expression of bre-3 and bre-5 mRNA in DBM1Ac-R from 3th to mature larvae and the long-term Cry1Ac toxin selection to DBM1Ac-R strain.In the same stage of DBM1Ac-S and DBM1Ac-R strains,the mRNA level expression of bre-5 was higher than bre-3,showing obvious advantage of gene expression.These findings will provide important basis for further study on GSLs,one of the receptors of Bacillus thuringiensis crystal proteins.