Identification of potential detoxification enzyme genes in Leptinotarsa decemlineata (Say) and study of their expression in insects reared on different plants

Abstract

Insects have evolved remarkable abilities to metabolize plant allelochemicals colonizing host plants otherwise toxic to them. These abilities largely rely on detoxification enzymes such as cytochromes P450 (P450), glutathione S-transferases (GST) and esterases. To identify the potential detoxification enzyme genes in Leptinotarsa decemlineata (Say), 44 expressed sequence tags (ESTs) including the ESTs of 38 P450, three GSTs and three esterases were generated using a degenerate rapid amplification of cDNA ends (RACE). The putative P450s were placed into 10 subfamilies representing five families. The gene expression was studied using a low-density reverse Northern array. The results showed that CYP4BN13v1 was up-regulated after the beetles transferred from potato to tomato, pepper or eggplant. The expression of CYP4Q11 was up-regulated in the beetles transferred to eggplants. In contrast, the expression of CYP9Z14v1 and CYP4BN13v1 was down-regulated after the beetles transferred to eggplant or flowering tobacco, respectively. This indicates that only a few P450 genes from the insect were induced or suppressed by different rearing plants. Although the function of these P450 enzymes in the metabolism of allelochemicals was not determined here, the result implies that the insect may use different oxidative metabolic pathways when they feed on different host plants. Key words: Cytochrome P450, glutathione S-transferase, esterase, gene expression, host plant