Comparative Transcriptomic Analysis Reveals Adaptation Mechanisms of Bean Bug Riptortus pedestris to Different Food Resources

Abstract

The bean bug, Riptortus pedestris (Hemiptera: Heteroptera), poses a significant threat to soybean production, resulting in substantial crop losses. Throughout the soybean cultivation period, these insects probe and suck on various parts of plants, including leaves, pods, and beans. However, the specific mechanisms by which they adapt to different food resources remain unknown. In this study, we conducted gut transcriptomic analyses of R. pedestris fed with soybean leaves, pods, and beans. A total of 798, 690, and 548 differently expressed genes (DEGs) were monitored in G—pod vs. G—leaf (comparison of insect feeding on pods and leaves), G—bean vs. G—leaf (comparison of insect feeding on beans and leaves), and G—pod vs. G—bean (comparison of insect feeding on pods and beans), respectively. When fed on pods and beans, there was a significant increase in the expression of digestive enzymes, particularly cathepsins, serine proteases, and lipases. Conversely, when soybean leaves were consumed, detoxification enzymes, such as ABC transporters and 4-coumarate-CoA ligase, exhibited higher expression. Our findings indicate that R. pedestris dynamically regulates different metabolic pathways to cope with varying food resources, which may contribute to the development of effective strategies for managing this pest.

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

“…In the current study, notable variations in the expression level of RpedOBP37 were observed across different tissues when normalized to the most stable reference genes (EF1 and Actin) as well as an unstable reference gene (SDHA) (Figure 3). The detoxifying protein CYP6, which plays important roles in the response to oxidative stress in insects, demonstrates a wide distribution across various insect species [26]. When the expression levels of target genes were normalized using the most stable reference genes (EF1 and/or Actin), RpedCYP6 exhibited a consistent expression pattern.…”

“…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 .…”

“…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.…”