| Popis: |
Background: Hemiptera is one of the most speciose Orders of insects, and the most speciose considering hemimetabolous. Through their evolutive history, hemipterans with different feeding habits have adapted to deal with different chemical challenges. Three major gene families are involved in xenobiotic detoxification in insects: the cytochromes P450 (CYPs), carboxyl/cholinesterases (CCEs), and glutathione transferases (GSTs). Here we perform a comparative analysis on the complement of these gene superfamilies across five hemipteran species; four heteropterans (the plant feeders pentatomids Nezara viridula and Halyomorpha halys; the hematophagous Cimex lectularius, Cimicidae, and Rhodnius prolixus, Reduviidae), and one plant feeder Auchenorryncha (Nilaparvata lugens). Results: Our results point to an expansion of several enzyme families associated to xenobiotic detoxification in heteropterans respect to other species, and present a dynamic evolution pattern including CYP3 clan, hormone and pheromone processing class in the CCE superfamily and Sigma class in GST superfamily. Other detoxification-related families are reduced in the Hemiptera species analyzed here: reduction or even absence of class Epsilon and reduced class Delta in GST superfamily; absence of mitochondrial family CYP12; absence of CYP9 family in CYP3 clan; and reduction or even absence of some dietary/detoxification groups of CCEs. Interestingly, the most polyphagous species analyzed here (H. halys), is also the one that presents the larger repertoire of detoxification enzymes. Gene-cluster analysis suggests that this could be due to gene duplication events. Conclusions: The evolutionary analysis performed here reveals characteristics that are both common and particular for heteropterans. The composition and organization of detox-related gene families could shed light on evolutionary forces that shaped their divergence. These families are both important for the detoxification of diet products and to confer tolerance or resistance to synthetic insecticides. Furthermore, we present here the first comprehensive analysis of detoxificant gene superfamilies in N. viridula, an understudied species in spite of its economic relevance as a crop pest. The information obtained is of interest for basic insect science, as much as for the control of harmful species and the management of insecticide resistance. |
