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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.


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The changes of endogenous IAA level (A–F) and PtrFBL expression (G,H) under NAA treatment. (A) Untreated control; (B) NAA, treated 10 min; (C) NAA, treated 20 min; (D) NAA, treated 30 min; (E) NAA, treated 60 min; (F) NAA, treated 360 min. (G) Relative expression of PtrFBLs in 84k leaves after NAA treatments. (H) Relative expression of PtrFBLs in 84k stems after NAA treatments. Bars, 1 cm (A–F), *indicates significant difference at P < 0.05.
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Figure 4: The changes of endogenous IAA level (A–F) and PtrFBL expression (G,H) under NAA treatment. (A) Untreated control; (B) NAA, treated 10 min; (C) NAA, treated 20 min; (D) NAA, treated 30 min; (E) NAA, treated 60 min; (F) NAA, treated 360 min. (G) Relative expression of PtrFBLs in 84k leaves after NAA treatments. (H) Relative expression of PtrFBLs in 84k stems after NAA treatments. Bars, 1 cm (A–F), *indicates significant difference at P < 0.05.

Mentions: To reveal whether PtrFBL genes respond to auxin, we analyzed the expression profiles of PtrFBLs in poplar treated with NAA. We used poplar lines with DR5::GUS as an auxin marker (Liu et al., 2014a) to monitor the response of auxin in whole seedlings under NAA treatment (Figures 4A–F), which showed that the endogenous auxin response decreased at an early stage then increased gradually. The PtrFBL transcripts in general were not significantly affected by NAA treatment as quantified by qRT-PCR (Figures 4G,H). The limited responses of PtrFBLs to NAA treatment in Populus in this study and in Arabidopsis (Parry et al., 2009) indicated that FBLs were not very sensitive to auxin. However, a considerably lower expression levels of PtrFBL1 and 7, which showed unique expression patterns in the cambial zone (Figure 3), were observed in stems after NAA treatment (Figures 4G,H). This may suggest their specific functions in vascular tissue development.


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)

The changes of endogenous IAA level (A–F) and PtrFBL expression (G,H) under NAA treatment. (A) Untreated control; (B) NAA, treated 10 min; (C) NAA, treated 20 min; (D) NAA, treated 30 min; (E) NAA, treated 60 min; (F) NAA, treated 360 min. (G) Relative expression of PtrFBLs in 84k leaves after NAA treatments. (H) Relative expression of PtrFBLs in 84k stems after NAA treatments. Bars, 1 cm (A–F), *indicates significant difference at P < 0.05.
© Copyright Policy
Related In: Results  -  Collection

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Figure 4: The changes of endogenous IAA level (A–F) and PtrFBL expression (G,H) under NAA treatment. (A) Untreated control; (B) NAA, treated 10 min; (C) NAA, treated 20 min; (D) NAA, treated 30 min; (E) NAA, treated 60 min; (F) NAA, treated 360 min. (G) Relative expression of PtrFBLs in 84k leaves after NAA treatments. (H) Relative expression of PtrFBLs in 84k stems after NAA treatments. Bars, 1 cm (A–F), *indicates significant difference at P < 0.05.
Mentions: To reveal whether PtrFBL genes respond to auxin, we analyzed the expression profiles of PtrFBLs in poplar treated with NAA. We used poplar lines with DR5::GUS as an auxin marker (Liu et al., 2014a) to monitor the response of auxin in whole seedlings under NAA treatment (Figures 4A–F), which showed that the endogenous auxin response decreased at an early stage then increased gradually. The PtrFBL transcripts in general were not significantly affected by NAA treatment as quantified by qRT-PCR (Figures 4G,H). The limited responses of PtrFBLs to NAA treatment in Populus in this study and in Arabidopsis (Parry et al., 2009) indicated that FBLs were not very sensitive to auxin. However, a considerably lower expression levels of PtrFBL1 and 7, which showed unique expression patterns in the cambial zone (Figure 3), were observed in stems after NAA treatment (Figures 4G,H). This may suggest their specific functions in vascular tissue development.

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