Detect Cytochrome C Oxidase- and Glutathione-S-Transferase-Mediated Detoxification in a Permethrin-Resistant Population of Lygus lineolaris.

ABSTRACT

Frequent sprays on cotton prompted resistance development in the tarnished plant bug (TPB). Knowledge of global gene regulation is highly desirable to better understand resistance mechanisms and develop molecular tools for monitoring and managing resistance. Novel microarray expressions of 6688 genes showed 3080 significantly up- or down-regulated genes in permethrin-treated TPBs. Among the 1543 up-regulated genes, 255 code for 39 different enzymes, and 15 of these participate in important pathways and metabolic detoxification. Oxidase is the most abundant and over-expressed enzyme. Others included dehydrogenases, synthases, reductases, and transferases. Pathway analysis revealed several oxidative phosphorylations associated with 37 oxidases and 23 reductases. One glutathione-S-transferase (GST LL_2285) participated in three pathways, including drug and xenobiotics metabolisms and pesticide detoxification. Therefore, a novel resistance mechanism of over-expressions of oxidases, along with a GST gene, was revealed in permethrin-treated TPB. Reductases, dehydrogenases, and others may also indirectly contribute to permethrin detoxification, while two common detoxification enzymes, P450 and esterase, played less role in the degradation of permethrin since none was associated with the detoxification pathway. Another potential novel finding from this study and our previous studies confirmed multiple/cross resistances in the same TPB population with a particular set of genes for different insecticide classes.