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A Populus TIR1 gene family survey reveals differential expression patterns and responses to 1-naphthaleneacetic acid and stress treatments.

Shu W, Liu Y, Guo Y, Zhou H, Zhang J, Zhao S, Lu M - Front Plant Sci (2015)

Bottom Line: Interestingly, PtrFBL1 and 7 were expressed mainly in vascular and cambial tissues, respectively, indicating their potential but different roles in wood formation.Finally, over-expression studies indicated a role of FBL1 in poplar stem growth and response to drought stress.Collectively, these observations lay the foundation for further investigations into the potential roles of PtrFBL genes in tree growth and development.

View Article: PubMed Central - PubMed

Affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University Nanjing, China ; State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.

ABSTRACT
The plant hormone auxin is a central regulator of plant growth. TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX (TIR1/AFB) is a component of the E3 ubiquitin ligase complex SCF(TIR1/AFB) and acts as an auxin co-receptor for nuclear auxin signaling. The SCF(TIR1/AFB)-proteasome machinery plays a central regulatory role in development-related gene transcription. Populus trichocarpa, as a model tree, has a unique fast-growth trait to which auxin signaling may contribute. However, no systematic analyses of the genome organization, gene structure, and expression of TIR1-like genes have been undertaken in this woody model plant. In this study, we identified a total of eight TIR1 genes in the Populus genome that are phylogenetically clustered into four subgroups, PtrFBL1/PtrFBL2, PtrFBL3/PtrFBL4, PtrFBL5/PtrFBL6, and PtrFBL7/PtrFBL8, representing four paralogous pairs. In addition, the gene structure and motif composition were relatively conserved in each paralogous pair and all of the PtrFBL members were localized in the nucleus. Different sets of PtrFBLs were strongly expressed in the leaves, stems, roots, cambial zones, and immature xylem of Populus. Interestingly, PtrFBL1 and 7 were expressed mainly in vascular and cambial tissues, respectively, indicating their potential but different roles in wood formation. Furthermore, Populus FBLs responded differentially upon exposure to various stresses. Finally, over-expression studies indicated a role of FBL1 in poplar stem growth and response to drought stress. Collectively, these observations lay the foundation for further investigations into the potential roles of PtrFBL genes in tree growth and development.

No MeSH data available.


Related in: MedlinePlus

Expression profiles of PtrFBL genes under heat and drought treatments. (A) Heat map showing eight PtrFBL genes under heat stress. 2 h: 2 h of 37°C heat treatment; R2h: 2 h recovery after 37°C heat treatment. Endogenous IAA levels expressed in DR5-GUS plants under PEG6000 stress (B–G); (B) 0 h, (C) 0.5 h, (D) 3 h, (E) 6 h, (F) 12 h, and (G) 24 h treatments; (H,I) Expression profiles of eight PtrFBL genes under PEG6000 stress; (H) in 84k leaf; (I) in 84k stems. Bars, 1 cm (B–G), *indicates significant difference at P < 0.05.
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Figure 5: Expression profiles of PtrFBL genes under heat and drought treatments. (A) Heat map showing eight PtrFBL genes under heat stress. 2 h: 2 h of 37°C heat treatment; R2h: 2 h recovery after 37°C heat treatment. Endogenous IAA levels expressed in DR5-GUS plants under PEG6000 stress (B–G); (B) 0 h, (C) 0.5 h, (D) 3 h, (E) 6 h, (F) 12 h, and (G) 24 h treatments; (H,I) Expression profiles of eight PtrFBL genes under PEG6000 stress; (H) in 84k leaf; (I) in 84k stems. Bars, 1 cm (B–G), *indicates significant difference at P < 0.05.

Mentions: Temperature was an important factor that limits the growth, development, and geographical distribution of plants (Nguyen et al., 2009), and high temperatures altered auxin responses by changing auxin synthesis (Franklin et al., 2011). We investigated the expression of the PtrFBL genes based on our RNA-seq data (unpublished) from heat-treated seedlings by transferring them from 25 to 37°C and incubating for 2 h. The results showed the different responses of PtrFBL members under heat stress (Figure 5A). Previous studies in Arabidopsis found that the quadruple mutant tir1/afb1/afb2/afb3 exhibited a delayed response but also a strongly reduced hyponastic growth response amplitude after the initiation of the heat treatment (van Zanten et al., 2009). Therefore, FBLs are among the primary factors involved in heat stress response.


A Populus TIR1 gene family survey reveals differential expression patterns and responses to 1-naphthaleneacetic acid and stress treatments.

Shu W, Liu Y, Guo Y, Zhou H, Zhang J, Zhao S, Lu M - Front Plant Sci (2015)

Expression profiles of PtrFBL genes under heat and drought treatments. (A) Heat map showing eight PtrFBL genes under heat stress. 2 h: 2 h of 37°C heat treatment; R2h: 2 h recovery after 37°C heat treatment. Endogenous IAA levels expressed in DR5-GUS plants under PEG6000 stress (B–G); (B) 0 h, (C) 0.5 h, (D) 3 h, (E) 6 h, (F) 12 h, and (G) 24 h treatments; (H,I) Expression profiles of eight PtrFBL genes under PEG6000 stress; (H) in 84k leaf; (I) in 84k stems. Bars, 1 cm (B–G), *indicates significant difference at P < 0.05.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4585115&req=5

Figure 5: Expression profiles of PtrFBL genes under heat and drought treatments. (A) Heat map showing eight PtrFBL genes under heat stress. 2 h: 2 h of 37°C heat treatment; R2h: 2 h recovery after 37°C heat treatment. Endogenous IAA levels expressed in DR5-GUS plants under PEG6000 stress (B–G); (B) 0 h, (C) 0.5 h, (D) 3 h, (E) 6 h, (F) 12 h, and (G) 24 h treatments; (H,I) Expression profiles of eight PtrFBL genes under PEG6000 stress; (H) in 84k leaf; (I) in 84k stems. Bars, 1 cm (B–G), *indicates significant difference at P < 0.05.
Mentions: Temperature was an important factor that limits the growth, development, and geographical distribution of plants (Nguyen et al., 2009), and high temperatures altered auxin responses by changing auxin synthesis (Franklin et al., 2011). We investigated the expression of the PtrFBL genes based on our RNA-seq data (unpublished) from heat-treated seedlings by transferring them from 25 to 37°C and incubating for 2 h. The results showed the different responses of PtrFBL members under heat stress (Figure 5A). Previous studies in Arabidopsis found that the quadruple mutant tir1/afb1/afb2/afb3 exhibited a delayed response but also a strongly reduced hyponastic growth response amplitude after the initiation of the heat treatment (van Zanten et al., 2009). Therefore, FBLs are among the primary factors involved in heat stress response.

Bottom Line: Interestingly, PtrFBL1 and 7 were expressed mainly in vascular and cambial tissues, respectively, indicating their potential but different roles in wood formation.Finally, over-expression studies indicated a role of FBL1 in poplar stem growth and response to drought stress.Collectively, these observations lay the foundation for further investigations into the potential roles of PtrFBL genes in tree growth and development.

View Article: PubMed Central - PubMed

Affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University Nanjing, China ; State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.

ABSTRACT
The plant hormone auxin is a central regulator of plant growth. TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX (TIR1/AFB) is a component of the E3 ubiquitin ligase complex SCF(TIR1/AFB) and acts as an auxin co-receptor for nuclear auxin signaling. The SCF(TIR1/AFB)-proteasome machinery plays a central regulatory role in development-related gene transcription. Populus trichocarpa, as a model tree, has a unique fast-growth trait to which auxin signaling may contribute. However, no systematic analyses of the genome organization, gene structure, and expression of TIR1-like genes have been undertaken in this woody model plant. In this study, we identified a total of eight TIR1 genes in the Populus genome that are phylogenetically clustered into four subgroups, PtrFBL1/PtrFBL2, PtrFBL3/PtrFBL4, PtrFBL5/PtrFBL6, and PtrFBL7/PtrFBL8, representing four paralogous pairs. In addition, the gene structure and motif composition were relatively conserved in each paralogous pair and all of the PtrFBL members were localized in the nucleus. Different sets of PtrFBLs were strongly expressed in the leaves, stems, roots, cambial zones, and immature xylem of Populus. Interestingly, PtrFBL1 and 7 were expressed mainly in vascular and cambial tissues, respectively, indicating their potential but different roles in wood formation. Furthermore, Populus FBLs responded differentially upon exposure to various stresses. Finally, over-expression studies indicated a role of FBL1 in poplar stem growth and response to drought stress. Collectively, these observations lay the foundation for further investigations into the potential roles of PtrFBL genes in tree growth and development.

No MeSH data available.


Related in: MedlinePlus