Characterization of Two Small Heat Shock Protein Genes (Hsp17.4 and Hs20.3) from Sitodiplosis mosellana, and Their Expression Regulation during Diapause

Abstract

Sitodiplosis mosellana, a periodic but devastating wheat pest that escapes temperature extremes in summer and winter by undergoing obligatory diapause. To determine the roles of small heat shock proteins (sHsps) in diapause of S. mosellana, we characterized two sHsp genes, SmHsp17.4 and SmHsp20.3, from this species. Both SmHsps contained the conserved α-crystallin domain and the carboxy-terminal I/VXI/V motif of the sHsp family. SmHsp17.4 had one intron while SmHsp20.3 had none. Quantitative PCR revealed that SmHsp17.4 expression decreased after diapause initiation, but substantially increased during transition to post-diapause quiescence. In contrast, SmHsp20.3 expression was not affected by entry of diapause, but was clearly up-regulated during summer and winter. Short-term more severe heat-stress (≥35 °C) of over-summering larvae or cold-stress (≤−5 °C) of over-wintering larvae could stimulate higher expression of both genes, and SmHsp17.4 was more responsive to cold stress while SmHsp20.3 was more sensitive to heat stress. Notably, transcription of SmHsp17.4, but not SmHsp20.3, in diapausing larvae was inducible by 20-hydroxyecdysone (20E). Recombinant SmHsp17.4 and SmHsp20.3 proteins also displayed significant chaperone functionality. These findings suggest that both SmHsps play key roles in stress tolerance during diapause; and 20E-regulated SmHsp17.4 was also likely involved in diapause termination.

Prolonged Heat Stress during Winter Diapause Alters the Expression of Stress-Response Genes in Ostrinia nubilalis (Hbn.)

“…Acting independently of ATP, they are the first line of cell defense, preventing the irreversible denaturation of substrate proteins, especially when cells are stressed [ 18 ]. Small HSPs have been extensively studied in diapausing insects, including the fruit flies Drosophila triauraria and D. melanogaster [ 23 , 81 ], the flesh fly, S. crassipalpis [ 96 ], the corn stalk borer S. nonagrioides [ 70 ], the wheat midge S. mosellana [ 97 ], the butterfly Pieris melete [ 98 ], the leaf beetle Gastrophysa atrocyanea [ 99 ] and the silkworm B. mori [ 100 ]. The augmentation of sHSPs appears to be common during diapause in numerous species across different insect orders, including Lepidoptera, Diptera, Hymenoptera and Coleoptera, and can occur at different developmental stages (embryo, larva, pupa, adult) [ 72 ].…”

The Implication Inferred from the Expression of Small Heat-Shock Protein Genes in Dinoflagellate Resting Cysts Buried in Marine Sediment

“…Many insects undergo a developmental process of seasonal dormancy termed "diapause", which offers an adaptive advantage to survive adverse environments and allows life cycle synchronization with suitable periods for growth, development, and reproduction [50]. Several studies have shown that insects' sHsps are associated with the diapause process and their implication during diapause might be quite different amongst different insect species [50,[55][56][57][58].…”

Research Progress on Diapause in Flies (Diptera)

“…A proteomic approach was used to investigate the proteins extracted from larvae of S. mosellana at different developmental stages, which include pre-diapause, over-summering diapause, Research Progress on Diapause in Flies (Diptera) DOI: http://dx.doi.org/10.5772/intechopen.106158 over-wintering diapause, and post-diapause. The results showed that two small Hsps play key roles in stress tolerance during diapause [62]. Proteins synthesized by pupal brains of the flesh fly S. crassipalpis were examined during diapause and non-diapause using pulse labeling and two-dimensional electrophoresis, and it was found that a cluster of about 15 brain proteins appears to be specific to diapausing pupae [63].…”