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Characterization of Two Novel Heat Shock Protein 70 Transcripts from Sitodiplosis mosellana and Their Response to Larval Diapause and Thermal Stress
by
,
Qitong Huang
1,2
,
Wenqian Tang
1,
Xiaobin Liu
1,
Qian Ma
2,
Keyan Zhu-Salzman
3,* and
Weining Cheng
2,* 1
Shandong Institute of Sericulture, Shandong Academy of Agricultural Sciences, Yantai 265503, China
2
Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling 712100, China
3
Department of Entomology, Texas A&M University, College Station, TX 77843, USA
*
Authors to whom correspondence should be addressed.
Biology 2025, 14(9), 1147; https://doi.org/10.3390/biology14091147 (registering DOI)
Submission received: 7 August 2025
/
Revised: 28 August 2025
/
Accepted: 29 August 2025
/
Published: 30 August 2025
Simple Summary
The heat shock protein 70 (Hsp70) family plays key roles not only in heat/cold stress tolerance but also in insect diapause. In this study, we characterized two cytoplasmic Hsp70 genes (SmHsp70A1-1 and SmHsp70A1-2) from Sitodiplosis mosellana, a major wheat pest undergoing obligatory diapause as third-instar larvae in the soil, and analyzed their expression profiles and functions in relation to diapause and thermal stress. The results showed that the expression of SmHsp70A1-1 and SmHsp70A1-2 is developmentally and environmentally regulated, with increased expression being essential for enhancing cold tolerance in S. mosellana. The findings provide crucial insights into the mechanisms underlying thermal tolerance in this pest.
Abstract
The heat shock protein 70 (Hsp70) family mediates responses to environmental stress in insects. The wheat midge Sitodiplosis mosellana, a worldwide pest, avoids summer and winter temperature extremes by diapause of the third-instar larvae in the soil. To explore the functions of Hsp70s in this process, we characterized two cytoplasmic Hsp70 genes (SmHsp70A1-1 and SmHsp70A1-2) from this insect. Both SmHsp70s contained three signature motifs of the family and lacked introns. Developmental expression profiling revealed maximal SmHsp70A1-1 expression during early larval stages, while the expression of SmHsp70A1-2 was highest in the pupal stages. The expression of SmHsp70A1-1 was significantly upregulated during diapause, particularly during summer and winter, whereas SmHsp70A1-2 showed marked downregulation and dose-dependent induction by 20-hydroxyecdysone (20E). Furthermore, both genes exhibited similar expression patterns in over-summering and over-wintering larvae under thermal stress, with maximal expression at 40 °C and −10 °C, respectively, but were not significantly induced at prolonged extreme temperatures (50 °C or −15 °C). Knockdown of the two SmHsp70 genes by RNA interference (RNAi) significantly increased the susceptibility of the larvae to cold stress. These results suggest the important role of both SmHsp70 genes in diapause-associated stress tolerance and provide crucial insights into the mechanisms underlying thermal adaptation in S. mosellana.
