A three amino acid deletion in the transmembrane domain of the nicotinic acetylcholine receptor alpha 6 subunit confers high-level resistance to spinosad in Plutella xylostella

作者：Wang, Jing; Wang, Xingliang; Lansdell, Stuart J.; Zhang, Jianheng; Millar, Neil S.; Wu, Yidong^*

来源：Insect Biochemistry and Molecular Biology, 2016, 71: 29-36.

DOI：10.1016/j.ibmb.2016.02.001

• Plutella xylostella
• Spinosad
• Nicotinic acetylcholine receptor
• Deletion
• Insecticide resistance

Spinosad is a macrocyclic lactone insecticide that acts primarily at the nicotinic acetylcholine receptors (nAChRs) of target insects. Here we describe evidence that high levels of resistance to spinosad in the diamondback moth (Plutella xylostella) are associated with a three amino acid (3-aa) deletion in the fourth transmembrane domain (TM4) of the nAChR alpha 6 subunit (Px alpha 6). Following laboratory selection with spinosad, the SZ-SpinR strain of P. xylostella exhibited 940-fold resistance to spinosad. In addition, the selected insect population had 1060-fold cross-resistance to spinetoram but, in contrast, no cross resistance to abamectin was observed. Genetic analysis indicates that spinosad resistance in SZ-SpinR is inherited as a recessive and autosomal trait, and that the 3-aa deletion (IIA) in TM4 of Px alpha 6 is tightly linked to spinosad resistance. Because of well-established difficulties in functional expression of cloned insect nAChRs, the analogous resistance-associated deletion mutation was introduced into a prototype nAChR (the cloned human alpha 7 subunit). Two-electrode voltage-clamp recording with wild-type and mutated nAChRs expressed in Xenopus laevis oocytes indicated that the mutation causes a complete loss of agonist activation. In addition, radioligand binding studies indicated that the 3-aa deletion resulted in significantly lower-affinity binding of the extracellular neurotransmitter-binding site. These findings are consistent with the 3-amino acid (IIA) deletion within the transmembrane domain of Px alpha 6 being responsible for target-site resistance to spinosad in the SZ-SpinR strain of P. xylostella.

• 出版日期2016-4
• 单位南京农业大学