Genomics-based approaches to screening carboxylesterase-like genes potentially involved in malathion resistance in oriental migratory locust (Locusta migratoria manilensis).
BACKGROUND
Previous studies have indicated that increased carboxylesterase (CarE) activity is a major mechanism of malathion resistance in field populations of the oriental migratory locust, Locusta migratoria manilensis (Meyen), in China. The aim of the present study was to screen CarE-like genes from a large locust expressed sequence tag (EST) database and to assess their potential roles in malathion resistance.


RESULTS
Twenty-five ESTs derived from different CarE-like genes in the locust EST database were identified, and 12 candidate genes with significantly increased expressions, ranging from 2.6- to 11.6-fold in a field-derived resistant (FR) colony of the locust, were found. These candidate genes were constitutively expressed in all nymph and adult stages, and most of them were predominantly expressed in the gastric caeca and the midgut. Among the 12 genes, two representative genes (LmCarE9 and LmCarE25) were chosen for RNAi followed by malathion bioassay. The nymph mortalities increased from 34.3 to 65.2 and 54.2% respectively after LmCarE9 and LmcarE25 were silenced. These results indicated significant roles of these CarE-like genes in conferring malathion resistance in the locust.


CONCLUSIONS
Multiple CarE-like genes were involved in malathion resistance in the locust. As validated by RNAi followed by malathion bioassay, LmCarE9 and LmcarE25 played a significant role in conferring malathion resistance.
Research Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi, China.
Jianzhen
J
Zhang
Jianqin
J
Zhang
Meiling
M
Yang
Qidong
Q
Jia
Yaping
Y
Guo
Enbo
E
Ma
Kun Yan
KY
Zhu
D025041:Animal Migration; D000818:Animals; D043182:Carboxylesterase / Q000235:genetics* / Q000378:metabolism; D030561:Databases, Nucleic Acid; D020224:Expressed Sequence Tags; D023281:Genomics; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D048188:Locusta migratoria / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D008294:Malathion / Q000494:pharmacology*
D019476:Insect Proteins; D007306:Insecticides; D043182:Carboxylesterase; D008294:Malathion