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Extensive gene duplication of acetylcholinesterase associated with organophosphate resistance in the two‐spotted spider mite
Author(s) -
Kwon D. H.,
Clark J. M.,
Lee S. H.
Publication year - 2010
Publication title -
insect molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.955
H-Index - 93
eISSN - 1365-2583
pISSN - 0962-1075
DOI - 10.1111/j.1365-2583.2009.00958.x
Subject(s) - biology , spider mite , tetranychus urticae , gene duplication , monocrotophos , gene , acetylcholinesterase , genetics , strain (injury) , organophosphate , tetranychus , mite , enzyme , botany , biochemistry , ecology , pesticide , anatomy
Monocrotophos‐resistant two‐spotted spider mites (TSSMs), Tetranychus urticae , are known to possess three mutations on the acetylcholinesterase (AChE) gene ( Tuace ) that are involved in target site insensitivity. Cross‐strain comparison of three strains (highly resistant AD, moderately resistant PyriF and susceptible UD strains) revealed that resistant strains have relatively more Tuace copies than the UD strain and that the levels of transcript were directly proportional to copy numbers. AChEs from the AD and PyriF strains had similar V max values to those of AChE from the UD strain but increased K m and reduced k cat constants, suggesting that the mutated, resistant form of AChE may carry a fitness cost. Relative copy numbers of Tuace in field populations varied from 2.4 to 6.1, correlating well with their levels of resistance ( r 2 = 0.895). These results are suggestive of the involvement of Tuace gene duplication in resistance. Thus, monocrotophos resistance in TSSMs appears to have evolved through a combination of mutation accumulation and extensive gene duplication.