Abstract
BackgroundHeat shock proteins (Hsps) are molecular chaperones that are involved in many normal cellular processes and stress responses, and heat shock factors (Hsfs) are the transcriptional activators of Hsps. Hsfs and Hsps are widely coordinated in various biological processes. Although the roles of Hsfs and Hsps in stress responses have been well characterized in Arabidopsis, their roles in perennial woody species undergoing various environmental stresses remain unclear.ResultsHere, a comprehensive identification and analysis of Hsf and Hsp families in poplars is presented. In Populus trichocarpa, we identified 42 paralogous pairs, 66.7% resulting from a whole genome duplication. The gene structure and motif composition are relatively conserved in each subfamily. Microarray and quantitative real-time RT-PCR analyses showed that most of the Populus Hsf and Hsp genes are differentially expressed upon exposure to various stresses. A coexpression network between Populus Hsf and Hsp genes was generated based on their expression. Coordinated relationships were validated by transient overexpression and subsequent qPCR analyses.ConclusionsThe comprehensive analysis indicates that different sets of PtHsps are downstream of particular PtHsfs and provides a basis for functional studies aimed at revealing the roles of these families in poplar development and stress responses.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1398-3) contains supplementary material, which is available to authorized users.
Highlights
Heat shock proteins (Hsps) are molecular chaperones that are involved in many normal cellular processes and stress responses, and heat shock factors (Hsfs) are the transcriptional activators of Hsps
The subcellular localization predictions suggested that the PtHsfs are targeted to the nucleus, while PtHsps are localized to various cytosolic organelles
To evaluate the evolutionary relationship of the Hsf and Hsp proteins, a phylogenetic analysis of each family was performed based on the full-length amino acid sequences from both P. trichocarpa and Arabidopsis (Figures 1 and 2, left panel)
Summary
Heat shock proteins (Hsps) are molecular chaperones that are involved in many normal cellular processes and stress responses, and heat shock factors (Hsfs) are the transcriptional activators of Hsps. The roles of Hsfs and Hsps in stress responses have been well characterized in Arabidopsis, their roles in perennial woody species undergoing various environmental stresses remain unclear. During their growth, plants are subjected to abiotic stresses, such as irradiation, temperature, salinity, and drought, and biotic stresses, such as herbivore and pathogen attacks. Heat shock proteins (Hsps) accumulate when the expression of their genes is triggered by heat, as well as other stresses [7,8,9]. The expression of Hsps is controlled and regulated by specific types of transcription factors called heat shock factors (Hsfs), which normally exist as inactive proteins [11]
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