Induced expression of small heat shock proteins is associated with thermotolerance in female Laodelphax striatellus planthoppers

Abstract

Insects are often exposed to high temperature stress in natural environments, but the mechanisms involved in thermotolerance in many insect groups like Hemiptera are not well known. To explore possible mechanisms of thermotolerance in the hemipteran pest Laodelphax striatellus, which damages rice through direct feeding and viral transmission, small heat shock proteins (sHsps) implicated in thermotolerance in other insect groups were identified. The seven sHsps identified have a conserved alpha crystallin domain, a variable N-terminal region, and shared relative low identities to each other. Three of the sHsp genes (LsHsp20.5, LsHsp21.5, and LsHsp21.6) exhibited higher basal expression than the other four genes but showed weak or no heat-induced expression. The other four genes (LsHsp20.1, LsHsp21.2, LsHsp21.4, and LsHsp22.0) were induced up to 3306-fold by heat. Injection of dsRNA indicated that expression of these sHsps was associated with thermotolerance, and Escherichia coli transformed with LsHsp21.2 and LsHsp20.1 showed relatively higher thermotolerance. These results point to an important functional role of these sHsps for thermotolerance in L. striatellus.

Identification and Expression Analysis of Four Small Heat Shock Protein Genes in Cigarette Beetle, Lasioderma serricorne (Fabricius)

“…Insects possess different types of sHsps, which differ in structure and function among species [23,24,27,47]. The sHsps are known to play major roles in cell response to different stresses [48].…”

“…Previous studies have demonstrated that sHsps play essential roles in insect development and in defense against a variety of stresses. For instance, sHsps contribute to thermal tolerance in Laodelphax striatellus [27]. The expression of three sHsp genes in flesh fly ( Sarcophaga crassipalpis ) is upregulated during overwintering pupal diapause [28].…”

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

“…We hypothesize that MaltHSP70-2 sustains its refolding activity and remains efficient when M. alternatus undergoes heat shock and this characteristic of MaltHSP70-2 plays a vital role in the heat tolerance of M. alternatus. Additionally, MaltHSP70-2 expression increased heat resistance in recombinant E. coli , and similar phenomena have been observed in studies on Apis cerana cerana and Laodelphax striatellus (Zhang et al ., 2014; Wang et al ., 2019 a ). These results indicate that MaltHSP70-2 expression could enhance cellular thermotolerance and support the hypothesis that MaltHSP70-2 is an important contributor to the mechanism of heat tolerance in M. alternatus .…”

“…ATPase activity was measured following the method described by Wang et al . (2019 a , 2019 b ) with slight modifications. Briefly, 100 μl reaction mixtures were created, with each containing 2.0 μg of purified HSP70/bovine serum albumin (BSA)/ddH 2 O, 1.0 mM Bis-Tris, 1.0 mM KCl, 0.1 mM MgCl 2 , and 0.01 mM ATP.…”

“…Since they were first discovered in Drosophila melanogaster larvae in 1962, HSP70 genes have been gradually identified and characterized in many insects, such as Tribolium castaneum , Bemisia tabaci , Locusta migratoria , Cydia pomonella , Lucilia sericata , and Megaphragma amalphitanum (Ritossa, 1962; Qin et al ., 2003; Rizana et al ., 2005; Tachibana et al ., 2005; Yin et al ., 2006; Chuvakova et al ., 2017; Wang et al ., 2019 a ). Both the transcript and protein levels of many HSP70s (PaptHAP70, AlucHSP70, and AovaHSP70) are significantly elevated after heat exposure, whereas the levels of HSC70 are only slightly increased (Vladimír et al ., 2009; Cheng et al ., 2016; Sun et al ., 2016; Xin et al ., 2018).…”