Identification and functional characterization of four TRPA1 variants in Apolygus lucorum (Meyer-Dür)

Authors: FU, TING - Institute Of Plant Protection - China; Hull, Joe; YANG, TING - Institute Of Plant Protection - China; WANG, GUIRONG - Institute Of Plant Protection - China

Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2016
Publication Date: 3/21/2016
Publication URL: http://handle.nal.usda.gov/10113/62960
Citation: Fu, T., Hull, J.J., Yang, T., Wang, G.R. 2016. Identification and functional characterization of four TRPA1 variants in Apolygus lucorum (Meyer-Dür). Insect Molecular Biology. 25(4):370–384.

Interpretive Summary: The green plant bug, Apolygus lucorum, is a pest of many crops throughout much of the world, and in recent years has become one the main pests of cotton in China. Control strategies have largely relied on pesticide applications. To begin developing novel biorational-based control strategies, genetic information recently made available for Apolygus was screened for gene candidates that can be targeted for disruption. One gene identified (i.e. TRPA1) produces a protein that senses both high temperatures and noxious compounds. The gene is expressed in sensory tissues and was activated by both heat and chemical treatment. The presence of multiple versions of the protein product produced by this gene suggests that different functions (i.e. heat sensation and perception of chemicals) are controlled by different versions. These findings enhance our understanding of how this pest species perceives environmental cues and provide a potential target for disruption. The findings can also be used to facilitate identification of similar genes and gene products in other species of plant bug pests, such as the western tarnished plant bug.

Technical Abstract: As signal integrators that respond to various physical and chemical stimuli, transient receptor potential (TRP) channels fulfil critical functional roles in the sensory systems of both vertebrate and invertebrate organisms. Here, four variants of TRP ankyrin 1 (TRPA1) were identified and cloned from the green plant bug, Apolygus lucorum. Spatiotemporal expression profiling across development and in different adult tissues revealed that the highest relative-transcript levels occurred in first-instar nymphs and antennae, respectively. In Xenopus laevis-based functional assays, Apo. lucorum TRPA1-A (AlucTRPA1-A), AlucTRPA1-B and AlucTRPA1-C were activated by increasing the temperature from 20 to 40 °C with no significant desensitization observed after repeated temperature stimuli. The activation temperature of AlucTRPA1-A and AlucTRPA1-B was'<'25 °C, whereas the activation temperature of AlucTRPA1-C was between 25 and 30 °C. Amongst the variants, only AlucTRPA1-A and AlucTRPA1-C were directly activated by high concentrations of allyl isothiocyanate, cinnamaldehyde and citronellal. Taken together, these results suggest that AlucTRPA1 variants may function in vivo as both thermal and chemical sensors, with the four variants potentially mediating different physiological functions. This study not only enriches our understanding of TRPA1 function in Hemiptera (Miridae), but also offers a foundation for developing new pest control strategies.