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Hsf and Hsp gene families in Populus: genome-wide identification, organization and correlated expression during development and in stress responses.

Zhang J, Liu B, Li J, Zhang L, Wang Y, Zheng H, Lu M, Chen J - BMC Genomics (2015)

Bottom Line: In Populus trichocarpa, we identified 42 paralogous pairs, 66.7% resulting from a whole genome duplication.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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China. zhang007jin@163.com.

ABSTRACT

Background: 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. 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.

Results: Here, 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.

Conclusions: The 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.

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qRT-PCR validation of transcriptional expression ofHspsregulated by transient overexpression ofPtHsfs. The relative mRNA abundance of selected three sHsps, three Hsp60s, three Hsp70s and three Hsp100s were quantified in transient overexpression leaves of PtHsfA2(A), PtHsfA6b(B), PtHsfB1(C), PtHsfB2a(D), and PtHsfB2b(E). The relative expressions represent log2 expression values. Asterisk, significant differences (P < 0.05) between overexpression and mock control.
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Fig10: qRT-PCR validation of transcriptional expression ofHspsregulated by transient overexpression ofPtHsfs. The relative mRNA abundance of selected three sHsps, three Hsp60s, three Hsp70s and three Hsp100s were quantified in transient overexpression leaves of PtHsfA2(A), PtHsfA6b(B), PtHsfB1(C), PtHsfB2a(D), and PtHsfB2b(E). The relative expressions represent log2 expression values. Asterisk, significant differences (P < 0.05) between overexpression and mock control.

Mentions: In Arabidopsis, some Hsfs have been shown to promote rapid Hsp expression by binding to cis-acting sequences, designated as heat shock elements (HSEs), in the promoter of Hsps [21,48]. To explore the potential regulatory network between PtHsfs and their downstream PtHsps, we constructed a coexpression network between PtHsfs and PtHsps using WGCNA [49]. As shown in Figure 9, there are many coexpression relationships between Populus Hsfs and Hsps, and one Hsf could be coexpressed with several Hsps. Moreover, several PtHsfs, including PtHsfA2, PtHsfA6a, and PtHsfB2a, showed high coexpression levels when bound to PtHsps. To validate the possible regulatory roles of PtHsfs, we transiently overexpressed PtHsfs in P. trichocarpa to detect the transcriptional regulation of the downstream PtHsps using qRT-PCR. Two type A Hsfs (PtHsfA2 and PtHsfA6a) and three type B Hsfs (PtHsfB1, PtHsfB2a, and PtHsfB2b) were selected for infiltration (see Methods). Three days after the infiltration of PtHsfs, the expression levels of selected Hsps (three sHsp, three Hsp60, three Hsp70, and three Hsp100) were examined to evaluate the transcriptional regulatory relationships between selected PtHsf and selected PtHsps (Figure 10).We revealed that, the expression levels of all of the detected Hsps, except 25.8VI-sHsp, were induced by the overexpression of PtHsfA2 (Figure 10A). One sHsps (18.1I-sHsp), two Hsp60s (Hsp60-1 and Cpn60-a1), three Hsp70s (Hsp70-5, mtHsc70-2, and cpHsc70-2), and two Hsp100s (Hsp100-ClpB2 and Hsp100-ClpB4) were significantly induced by the transient overexpression of PtHsfA6a, PtHsfB2a, and PtHsfB2b (Figure 10B, D, and E). However, only a few selected Hsps were induced by the overexpression of PtHsfB1 (Figure 10C).Figure 9


Hsf and Hsp gene families in Populus: genome-wide identification, organization and correlated expression during development and in stress responses.

Zhang J, Liu B, Li J, Zhang L, Wang Y, Zheng H, Lu M, Chen J - BMC Genomics (2015)

qRT-PCR validation of transcriptional expression ofHspsregulated by transient overexpression ofPtHsfs. The relative mRNA abundance of selected three sHsps, three Hsp60s, three Hsp70s and three Hsp100s were quantified in transient overexpression leaves of PtHsfA2(A), PtHsfA6b(B), PtHsfB1(C), PtHsfB2a(D), and PtHsfB2b(E). The relative expressions represent log2 expression values. Asterisk, significant differences (P < 0.05) between overexpression and mock control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4373061&req=5

Fig10: qRT-PCR validation of transcriptional expression ofHspsregulated by transient overexpression ofPtHsfs. The relative mRNA abundance of selected three sHsps, three Hsp60s, three Hsp70s and three Hsp100s were quantified in transient overexpression leaves of PtHsfA2(A), PtHsfA6b(B), PtHsfB1(C), PtHsfB2a(D), and PtHsfB2b(E). The relative expressions represent log2 expression values. Asterisk, significant differences (P < 0.05) between overexpression and mock control.
Mentions: In Arabidopsis, some Hsfs have been shown to promote rapid Hsp expression by binding to cis-acting sequences, designated as heat shock elements (HSEs), in the promoter of Hsps [21,48]. To explore the potential regulatory network between PtHsfs and their downstream PtHsps, we constructed a coexpression network between PtHsfs and PtHsps using WGCNA [49]. As shown in Figure 9, there are many coexpression relationships between Populus Hsfs and Hsps, and one Hsf could be coexpressed with several Hsps. Moreover, several PtHsfs, including PtHsfA2, PtHsfA6a, and PtHsfB2a, showed high coexpression levels when bound to PtHsps. To validate the possible regulatory roles of PtHsfs, we transiently overexpressed PtHsfs in P. trichocarpa to detect the transcriptional regulation of the downstream PtHsps using qRT-PCR. Two type A Hsfs (PtHsfA2 and PtHsfA6a) and three type B Hsfs (PtHsfB1, PtHsfB2a, and PtHsfB2b) were selected for infiltration (see Methods). Three days after the infiltration of PtHsfs, the expression levels of selected Hsps (three sHsp, three Hsp60, three Hsp70, and three Hsp100) were examined to evaluate the transcriptional regulatory relationships between selected PtHsf and selected PtHsps (Figure 10).We revealed that, the expression levels of all of the detected Hsps, except 25.8VI-sHsp, were induced by the overexpression of PtHsfA2 (Figure 10A). One sHsps (18.1I-sHsp), two Hsp60s (Hsp60-1 and Cpn60-a1), three Hsp70s (Hsp70-5, mtHsc70-2, and cpHsc70-2), and two Hsp100s (Hsp100-ClpB2 and Hsp100-ClpB4) were significantly induced by the transient overexpression of PtHsfA6a, PtHsfB2a, and PtHsfB2b (Figure 10B, D, and E). However, only a few selected Hsps were induced by the overexpression of PtHsfB1 (Figure 10C).Figure 9

Bottom Line: In Populus trichocarpa, we identified 42 paralogous pairs, 66.7% resulting from a whole genome duplication.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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China. zhang007jin@163.com.

ABSTRACT

Background: 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. 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.

Results: Here, 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.

Conclusions: The 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.

Show MeSH
Related in: MedlinePlus