Comparative Transcriptome Analysis of the Heat Stress Response in Monochamus alternatus Hope (Coleoptera: Cerambycidae)

Abstract

Temperature is a critical factor of insect population abundance and distribution. Monochamus alternatus Hope (Coleoptera: Cerambycidae) is a significant concern since it is transmitted vector of the pinewood nematode posing enormous economic and environmental losses. This pest shows tolerance to heat stress, especially extremely high temperatures. Exposing for 6, 12, 24, 48, or 96 h, the 50% median lethal temperatures (Ltem 50) for fourth-instar larvae were 47.5, 45.5, 43.9, 43.4, and 42.3 • C, respectively. A total of 63,360 unigenes were obtained from complementary DNA libraries of M. alternatus fourth-instar larvae (kept at 25 • C and exposed to 40 • C for 3 h) and annotated with six databases. Five hundred sixty-one genes were significantly upregulated, and 245 genes were downregulated after heat stress. The Gene Ontology enrichment analysis showed that most different expression genes are categorized into "protein folding" and "unfold protein binding" terms. In addition, "Longevity regulating pathway-multiple species," "Antigen processing and presentation" as well as "MAPK signaling pathway" were significantly enriched Kyoto Encyclopedia of Genes and Genomes pathways. Further analysis of different expression genes showed that metabolism processes were suppressed, while ubiquitin proteolytic system, heat shock proteins, immune response, superoxide dismutase, cytochrome P450s, and aldehyde dehydrogenase were induced after heat shock. The stress signaling transduction pathways such as MAPK, Hippo, and JAK-STAT might be central convergence points in M. alternatus heat tolerance mechanism. The expression levels from quantitative realtime PCR of 13 randomly selected genes were consistent with the transcriptome results. These results showed that M. alternatus possessed strong heat tolerance and genes related to protein activity, immune response, and signal transduction composed of a complicated heat tolerance mechanism of M. alternatus. This research provided new insights into the mechanisms of thermal tolerance in other insects and aided in exploring the function of heat resistance-related genes.

Characterization, expression profiling, and thermal tolerance analysis of heat shock protein 70 in pine sawyer beetle, Monochamus alternatus hope (Coleoptera: Cerambycidae)

“…The larvae of M. alternatus were obtained from infested host trees ( Pinus massoniana ) in Jiujiang, Jiangxi Province, China and reared individually on an artificial diet at a constant temperature of 25 ± 0.5°C under a relative humidity (RH) of 60 ± 5% as described by our previous experiment (Li et al ., 2020). Once emergence, adults were individually provided with fresh 1- to 2-year-old P. massoniana twigs.…”

“…M. alternatus showed strong heat tolerance in our previous study (Li et al ., 2020). Only appropriately 50% of the M. alternatus population was deadly damaged when exposed to 42.5°C for 96 h and almost all individuals could endure 40°C for 96 h. This property, in M. alternatus , was achieved for a broad array of adaptive strategies against adverse high temperature, c overing ecological, behavioral, and physiological aspects.…”

“…Only appropriately 50% of the M. alternatus population was deadly damaged when exposed to 42.5°C for 96 h and almost all individuals could endure 40°C for 96 h. This property, in M. alternatus , was achieved for a broad array of adaptive strategies against adverse high temperature, c overing ecological, behavioral, and physiological aspects. In terms of individual physiology, RNA-seq data from the heat exposure revealed that genes involved in protein activity, immune responses, and signal transduction constituted the heat tolerance mechanism of M. alternatus (Li et al ., 2020). Notably, the gene quantities, as well as the expression level of Heat Shock Proteins (HSPs) among the upregulated unigenes, were dominant in the physiological alterations (Li et al ., 2020).…”

“…In terms of individual physiology, RNA-seq data from the heat exposure revealed that genes involved in protein activity, immune responses, and signal transduction constituted the heat tolerance mechanism of M. alternatus (Li et al ., 2020). Notably, the gene quantities, as well as the expression level of Heat Shock Proteins (HSPs) among the upregulated unigenes, were dominant in the physiological alterations (Li et al ., 2020). Recently, it happened that there were similar cases confirming that HSPs commonly contribute to the physiological responses of insects to heat stress (Chen et al ., 2014; Luo et al ., 2015; Guo and Nian, 2018).…”

Transcriptomic Insights into the Insect Immune Response to Nematode Infection

“…The pinewood nematode, which is vectored by the pine sawyer beetle M. alternatus , is native to North America and is not considered a primary pathogen of native pines but is the cause of pine wilt in some non-native species [ 41 ]. Using global transcriptome information from previous studies that analyzed the response of M. alternatus to heat stress and pesticides [ 27 , 42 ], a recent comparative study expanded these findings by probing immune-related gene transcript changes in M. alternatus infected by B. xylophilus parasites [ 43 ]. Using high-throughput Illumina RNA-Seq, it was thoroughly demonstrated that the presence of B. xylophilus in M. alternatus adults alters the expression profile of a large number of genes with known or putative immune function.…”