Identification and expression analysis of four heat shock protein genes associated with thermal stress in rice weevil, Sitophilus oryzae.

Abstract In order to explore the function of heat shock proteins during thermal stress in rice weevil, Sitophilus oryzae , four heat shock protein genes were cloned and characterized. These heat shock protein genes ( hsps ) were named as Sohsp70–1 , Sohsp70–2 , Sohsc70 , and Sohsp90 , respectively. These hsps showed high sequence conservation with the maximum identity with hsps of Tribolium castaneum and other insects. All the four genes showed the highest mRNA expression in pupal stage and the lowest levels in larval stage. The induced expression of the two Sohsp70s ( Sohsp70–1 and Sohsp70–2 ) were reached to the highest levels (15.59-fold and 12.66-fold) after 2 h of incubation at 37 °C, respectively. Expression of Sohsp90 not only was significantly elevated by heat stress but also by cold stress. Whereas, expression level of Sohsc70 was not induced either by heat or cold stress. Furthermore, for rapid heat hardening, the expression levels of Sohsp70–1 , Sohsp70–2 , Sohsc70 and Sohsp90 were observed as 2.57, 2.53, 3.33 and 2.33-fold higher than control, respectively; for rapid cold hardening, the expression levels of Sohsp70–1 , Sohsp70–2 , Sohsc70 and Sohsp90 were reported as 2.27, 3.02, 3.37 and 2.23-fold higher than control, respectively. Hence, our results revealed that the four Sohsps were associated with temperature adaption under rapid heat or cold hardening. Graphical abstract Unlabelled Image Highlights • Four hsps genes ( Sohsp70–1 , Sohsp70–2 , Sohsc70 , and Sohsp90 ) were identified and characterized in S. oryzae. • Heat shock highly induced the Sohsps except Sohsc70 ; however, cold shock led to non- significant change. • The rapid heat or cold hardening resulted into induction of Sohsps and contributed to the thermotolerance of S.oryzae. [ABSTRACT FROM AUTHOR]