Metabolic detoxification of capsaicin by UDP‐glycosyltransferase in three Helicoverpa species

Abstract

Capsaicin β-glucoside was isolated from the feces of Helicoverpa armigera, Helicoverpa assulta, and Helicoverpa zea that fed on capsaicin-supplemented artificial diet. The chemical structure was identified by NMR spectroscopic analysis as well as by enzymatic hydrolysis. The excretion rates of the glucoside were different among the three species; those in the two generalists, H. armigera and H. zea, were higher than in a specialist, H. assulta. UDP-glycosyltransferases (UGT) enzyme activities measured from the whole larval homogenate of the three species with capsaicin and UDP-glucose as substrates were also higher in the two generalists. Compared among five different larval tissues (labial glands, testes from male larvae, midgut, the Malpighian tubules (MT), and fat body) from the three species, the formation of the capsaicin glucoside by one or more UGT is high in the fat body of all the three species as expected, as well as in H. assulta MT. Optimization of the enzyme assay method is also described in detail. Although the lower excretion rate of the unaltered capsaicin in H. assulta indicates higher metabolic capacity toward capsacin than in the other two generalists, the glucosylation per se seems to be insufficient to explain the decrease in capsaicin in the specialist, suggesting that H. assulta might have another important mechanism to deal with capsaicin more specifically.

Analysis of the Transcriptional Differences between Indigenous and Invasive Whiteflies Reveals Possible Mechanisms of Whitefly Invasion

“…In addition, P450s also play a significant role in insecticide resistance [59], [60]. UGTs belong to another family of enzymes involved in insect detoxification of plant allelochemicals and insecticides through glycosylation, which converts lipophilic aglycones into more hydrophilic glycosides, facilitating the excretion or sequestration for further utilization [61], [62]. Both MEAM1 and MED have a wide range of host plant, and MED is also known for its anti-insecticide ability.…”

Detection of environmental and morphological adaptation despite high landscape genetic connectivity in a pest grasshopper (Phaulacridium vittatum)

“…Uridine diphosphate-glucuronosyl transferase (UGT) is an important enzyme of the detoxification pathway and catalyses the addition of sugars to lipophilic compounds (Ahn et al, 2012). The detoxification role of UGT has also been well demonstrated in herbivorous insects (Ahn et al, 2011;Heidel-Fischer & Vogel, 2015) and pest insects (e.g., Krempl et al, 2016).…”

Antennal uridine diphosphate (UDP)‐glycosyltransferases in a pest insect: diversity and putative function in odorant and xenobiotics clearance

“…Insect UGTs typically use UDP‐glucose as a donor rather than UDP‐glucuronic acid (Ahmad & Hopkins, ; Luque & O'Reilly, ; Ahn et al ., ). UGT activities have been investigated in the fruit fly Drosophila melanogaster (Luque & O'Reilly, ), the grasshopper Melanoplus sanguinipes , the cockroach Periplaneta americana , two Tenebrio species and in several moths species (Ahmad & Hopkins, ; Luque et al ., ; Ahn et al ., ). These activities were mainly found in larvae and directed towards various ingested plant allelochemicals (Ahn et al ., , ).…”

“…UGT activities have been investigated in the fruit fly Drosophila melanogaster (Luque & O'Reilly, ), the grasshopper Melanoplus sanguinipes , the cockroach Periplaneta americana , two Tenebrio species and in several moths species (Ahmad & Hopkins, ; Luque et al ., ; Ahn et al ., ). These activities were mainly found in larvae and directed towards various ingested plant allelochemicals (Ahn et al ., , ). A recent phylogenetic analysis including 310 putative UGT genes identified from genomic/transcriptomic databases has shed a new light on the diversification of this multigene family in insects (Ahn et al ., ); however, only two UGTs were characterized both at the molecular and functional level in insects: a phenol‐UGT from Bombyx mori , which exhibited a wide substrate specificity towards allelochemicals (Huang et al ., ), and an UGT from Zygaena filipendulae , which has been involved in cyanogenic defence compound biosynthesis (Jensen et al ., ).…”