Genome-Wide Analysis of Odorant-Binding Proteins and Chemosensory Proteins in the Bean bug Riptortus pedestris

Abstract

Insects have sensitive olfactory systems to interact with environment and respond to the change in host plant conditions. Key genes in the system can be potential targets for developing new and efficient pest behaviour control methods. Riptortus pedestris is an important soybean pest in East Asia and has caused serious damage to the soybean plants in Huang-Huai-Hai region of China. However, the current treatment of pests is dominated by chemical insecticides and lacks efficient sustainable prevention and control technologies. In this study, we identified 49 putative odorant-binding proteins (OBPs) (43 were new genes) and 25 chemosensory proteins (CSPs) (17 were new genes) in R. pedestris genome. These OBP and CSP genes are clustered in highly conserved groups from other hemipteran species in phylogenetic trees. Most RpedOBPs displayed antennal-biased expression. Among the 49 RpedOBPs, 33 were significantly highly expressed in the antennae, including three male-biased and nine female-biased. While many RpedCSPs were detected both in the antennae and in non-antennal tissues, only 11 RpedCSPs displayed antennal-biased expression, in which four RpedCSPs were male-biased and five RpedCSPs were female-biased. Some OBP and CSP genes showed sex-biased expression profiles. Our results not only provide a foundation for future exploration of the functions of RpedOBPs and RpedCSPs but also aid in developing environmentally friendly insecticides in the future.

Evaluation of Reference Genes for Quantitative Real-Time PCR Analysis in the Bean Bug, Riptortus pedestris (Hemiptera: Alydidae)

“…The genomic and transcriptomic data of R. pedestris have been published to study its development, chemosensory genes, and insecticide resistance [20,[23][24][25]41,42]. Previous qRT-PCR studies on R. pedestris commonly employed universal reference genes for insect species [23][24][25][26]. Nevertheless, the use of inappropriate ones may result in misinterpretation of data.…”

“…We selected odorant-binding protein 37 (RpedOBP37) [25] and cytochrome P450 6a2 (RpedCYP6) [26] for the validation of the most stable reference genes (EF1 and Actin) and a variable one (SDHA). The forward primer and reverse sequences for Rpe-dOBP37 were 5 -ATGGGAGCGATTTCTGAT-3 and 5 -ATAGCGGTTTCACATCCA-3 , while the primer pairs for RpedCYP6 were 5 -TACGGTCGAGGTTATCTG-3 and 5 -GGGCTGGTTATCCTTACT-3 .…”

“…Fu et al identified numerous differentially expressed genes implicated in wing formation through a comparative analysis of the transcriptomes of R. pedestris eggs, first-, second-, third-, fourth-, and fifth-instar nymphs, as well as adults [23]. Moreover, Liu et al [24] and Li et al [25] conducted a transcriptional analysis of gene expression in the antennae of R. pedestris and identified several genes potentially involved in olfactory and taste transduction. The quantitative assessment of gene expression not only enhances the comprehension of the molecular mechanisms associated with insect development, stress response, and behavioral regulation in R. pedestris but also holds the potential to reveal novel targets for effective pest control.…”

“…Actin, EF1, and GAPDH have been employed as reference genes to normalize the expression of target genes implicated in the development, odor perception, odor discrimination, and behaviors (such as feeding and mating) of R. pedestris [23][24][25][26]. Nevertheless, the aforementioned studies did not assess the appropriateness of these genes in experimental conditions.…”

Identification, expression profiles, and binding properties of chemosensory protein 18 in Plutella xylostella (Lepidoptera: Plutellidae)

“…To date, the information available for CSPs, also known as sensory appendage proteins (SAPs), indicated that these small soluble proteins involved in diverse activities and endowed with heterogeneous functions, such as serving as carrier proteins for binding and delivering hydrophobic compounds in chemosensory process ( Robertson et al 1999 , Pelosi et al 2006 , 2018 , Fu et al 2020 ). Studies on the molecular structures suggested CSPs are constituted by 4 conserved cysteines, which arrangement mode shown as Cys 1 -X6-Cys 2 -X18-Cys 3 -X2-Cys 4 , and linked by disulfide bridges between 2 adjacent cysteine residues that resulted in the formation of 2 small loops ( Angeli et al 1999 , Zhu et al 2016 , Pelosi et al 2018 , Zeng et al 2019 , Li et al 2022 ). Research on the binding abilities showed that CSPs have good affinities with many chemicals, which later was identified that the 2 formed disulfide bridges do not place constraints on the scaffolding of the CSPs, so the proteins can enlarge their binding cavities and adapt to binding different components ( Yi et al 2014 , Pelosi et al 2018 ).…”