Abstract
The main function of small heat shock proteins (sHSPs) as molecular chaperones is to protect proteins from denaturation under adverse conditions. Molecular and physiological data were used to examine the sHSPs underlying cold-hardiness in Harmonia axyridis. Complementary DNA sequences were obtained for six H. axyridis sHSPs based on its transcriptome, and the expression of the genes coding for these sHSPs was evaluated by quantitative real-time PCR (qRT-PCR) in several developmental stages, under short-term cooling or heating conditions, and in black and yellow females of experimental and overwintering populations under low-temperature storage. In addition, we measured water content and the super cooling and freezing points (SCP and FP, respectively) of H. axyridis individuals from experimental and overwintering populations. The average water content was not significantly different between adults of both populations, but the SCP and FP of the overwintering population were significantly lower than that of the experimental population. Overall, the six sHSPs genes showed different expression patterns among developmental stages. In the short-term cooling treatment, Hsp16.25 and Hsp21.00 expressions first increased and then decreased, while Hsp10.87 and Hsp21.56 expressions increased during the entire process. Under short-term heating, the expressions of Hsp21.00, Hsp21.62, Hsp10.87, and Hsp16.25 showed an increasing trend, whereas Hsp36.77 first decreased and then increased. Under low-temperature storage conditions, the expression of Hsp36.77 decreased, while the expressions of Hsp21.00 and Hsp21.62 were higher than that of the control group in the experimental population. The expression of Hsp36.77 first increased and then decreased, whereas Hsp21.56 expression was always higher than that of the control group in the overwintering population. Thus, differences in sHSPs gene expression were correlated with the H. axyridis forms, suggesting that the mechanism of cold resistance might differ among them. Although, Hsp36.77, Hsp16.25, Hsp21.00, and Hsp21.62 regulated cold- hardiness, the only significant differences between overwintering and experimental populations were found for Hsp16.25 and Hsp21.00.
Highlights
Harmonia axyridis (Coleoptera: Coccinellidae) has strong predation ability on aphids, spider mites, mealy bugs, and other important pests, being an important natural enemy (Koch, 2003)
There was no significant difference in water content between sexes in the overwintering or experimental populations
The expression level of Hsp36.77 decreased in the experimental population (Figure 6A), FIGURE 6 | Relative expression of small HSPs (sHSPs) in the experimental population of Harmonia axyridis under the low-temperature storage treatment. (A) Hsp36.77. (B) Hsp16.25. (C) Hsp21.00. (D) Hsp21.62. (E) Hsp10.87. (F) Hsp21.56
Summary
Harmonia axyridis (Coleoptera: Coccinellidae) has strong predation ability on aphids, spider mites, mealy bugs, and other important pests, being an important natural enemy (Koch, 2003). Insects have evolved a variety of cold-resistance measures (Jing and Kang, 2002), mainly including ecological (or behavior) and physiological aspects Whereas, the former include migrating or hiding to avoid the damages caused by low temperature, the latter include regulating the body’s metabolic mechanisms and the accumulation of cold resistant compounds such as glycerol, trehalose, and polyol, among others (Watanabe, 2002; Guo et al, 2006; Gagnon et al, 2013). Studies indicated that insects moderating cold acclimation before low temperature stress have higher survival rate, lower lethal temperature, prolonged half-lethal time, and decreased SCP (Fields et al, 1998; Renault et al, 2004; Ma et al, 2006; Wang et al, 2006)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
