与拟除虫菊酯抗性相关的烟粉虱钠通道基因突变及其检测

通过RT-PCR克隆了烟粉虱Bemisia tabaci (Gennadius) 南京种群(B-生物型)的钠离子通道结构域ⅡS4-6 cDNA片段，证实了与拟除虫菊酯抗性相关的是位于第925位亮氨酸到异亮氨酸的突变(L925I)，并建立了L925I突变的PASA检测技术。与SUD-S敏感品系相比，2002年采自南京棉花上的烟粉虱种群对氯氰菊酯具有77倍的抗性，用氯氰菊酯对该种群进行多次筛选后，该种群对氯氰菊酯的抗药性提高到227倍。PASA检测结果表明筛选后的南京种群中100%个体都具有L925I突变(61.1%的个体为L925I突变纯合子，38.9%的个体为杂合子)，而未筛选的南京种群只有75%个体具有L925I突变(35%个体为L925I突变纯合子，40%的个体为杂合子，25%的个体为野生型)。该结果表明了烟粉虱钠离子通道L925I突变与对拟除虫菊酯抗性密切相关。还讨论了烟粉虱对拟除虫菊酯抗性的代谢机理。

A mutation in sodium channel gene associated with pyrethroid resistance in Bemisia tabaci (Gennadius) and its detection

A mutation, leucine to isoleucine at position 925 (L925I) in the ⅡS4-6 linker of the para-type sodium channel protein from the Nanjing strain (B-biotype) of the tobacco whitefly, Bemisia tabaci (Gennadius) was identified to be associated with pyrethroid resistance. The DNA-based genotyping technique PASA (PCR amplification of specific allele) for rapid detection of the L925I mutation was established. The Nanjing strain collected from cottons in Nanjing in 2002 showed 77-fold resistance to cypermethrin compared with the susceptible SUD-S strain. The resistance to cypermethrin in the selected Nanjing strain increased to 227-fold afterseveral selections with cypermethrin. PASA genotyping results indicated that 100 % individuals from the selected Nanjing strain had L925I mutation (61.1% homozyg otes and 38.9% heterozygotes), whereas only 75% individuals from the unselected Nanjing strain had L925I mutation (35% homozygotes, 40% heterozygotes and 25% wild type ). Our results indicated that L925I mutation was tightly associated with pyrethroid resistance in the tobacco whitefly from Nanjing. Possible metabolic mechanisms for pyrethroid resistance in this strain were discussed.