Molecular cloning and comparative analysis of transcripts encoding chemosensory proteins from two plant bugs, Lygus lineolaris and Lygus hesperus

Authors: Hull, Joe; Perera, Omaththage; WANG, MEIXIAN - Zhejiang University

Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2018
Publication Date: 6/13/2020
Citation: Hull, J.J., Perera, O.P., Wang, M. 2020. Molecular cloning and comparative analysis of transcripts encoding chemosensory proteins from two plant bugs, Lygus lineolaris and Lygus hesperus. Insect Science. 27:404-424. https://doi.org/10.1111/1744-7917.12656.
DOI: https://doi.org/10.1111/1744-7917.12656

Interpretive Summary: Insects perceive their host plants, mates, neighbors, and predators through chemical cues (odors, tastes). Sensory organs equipped with receptors that bind specific odor or taste molecules detect the chemical cues. Chemosensory proteins (CSPs) are among the specialized proteins thought to facilitate movement of the chemical cues from the outer parts of the sense organs to the receptors. Each CSP is constructed based on information in a transcript, or genetic template. Thus, one way to detect a CSP is to identify its transcript within various insect tissues. Based on analysis of thousands of transcripts from two insect pests of cotton and other economically important crops, the tarnished plant bug and the western tarnished plant bug, we identified 17 and 14 transcripts respectively with sequence features characteristic of CSPs. Most of the transcripts are predominantly expressed in sensory tissues, suggesting roles in olfaction (smell) and/or gustation (taste). These findings provide base-line information to guide future work on chemical communication in these insect pests. Better understanding of how these insect pests use and respond to chemical cues may lead to pest control technologies that interfere with essential chemical communications.

Technical Abstract: Chemosensory proteins (CSPs) are soluble carrier proteins typically characterized by a six-helix bundle structure joined by two disulfide bridges and a conserved Cys spacing pattern (C1-X6-8-C2-X16-21-C3-X2-C4). CSPs are functionally diverse with reported roles in chemosensation, immunity, development, and resistance. To expand our molecular understanding of CSP function in plant bugs, we used recently developed transcriptomic resources for Lygus lineolaris and Lygus hesperus to identify 17 and 14 CSP-like sequences, respectively. The Lygus CSPs are orthologous and share significant sequence identity with previously annotated CSPs. Three of the CSPs are predicted to deviate from the typical CSP structure with either five or seven helical segments rather than six. The seven helix CSP is further differentiated by an atypical C3-X3-C4 Cys spacing motif. Reverse transcriptase PCR-based profiling of CSP transcript abundance in adult L. lineolaris tissues revealed broad expression for most of the CSPs with antenna specific expression limited to a subset of the CSPs. Comparative sequence analyses and homology modeling suggest that variations in the amino acids that comprise the Lygus CSP binding pockets affects the size and nature of the ligands accommodated.