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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 growth and drought tolerance of PtrFBL1 over-expressed poplars. (A) Phenotypic changes in stem growth of over-expressing PtrFBL1; (B) Relative expression for over-expressing PtrFBL1; (C) The height and diameters of non- and transgenic lines; (D,E) Phenotypic changes of the PtrFBL1 over-expressed plants after drought treatment for 6 days and the photos were taken 15 days after rewatering. Bars, 5 cm (A,D,E), *indicates significant difference at P < 0.05, and **indicates extremely significant difference at P < 0.01.
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Figure 6: The growth and drought tolerance of PtrFBL1 over-expressed poplars. (A) Phenotypic changes in stem growth of over-expressing PtrFBL1; (B) Relative expression for over-expressing PtrFBL1; (C) The height and diameters of non- and transgenic lines; (D,E) Phenotypic changes of the PtrFBL1 over-expressed plants after drought treatment for 6 days and the photos were taken 15 days after rewatering. Bars, 5 cm (A,D,E), *indicates significant difference at P < 0.05, and **indicates extremely significant difference at P < 0.01.

Mentions: To investigate the role of PtrFBL1 in stem development, we successfully generated 84K transgenic lines constitutively over-expressing PtrFBL1 under the control of the 35S promoter. Three representative transgenic lines with relative expression over 14-fold were used for further analysis (Figures 6A,B). We observed apparent phenotypic changes in height and diameter of the transgenic plants (Figures 6A,C), which were significantly higher than that of the non-transgenic controls (P = 0.015 and P = 0.006, respectively). However, we found that the transgenic plants exhibited decreased tolerance under drought treatment (Figures 6D,E). RWC was a measure of plant water status and used as a meaningful index of water stress tolerance (Negi et al., 2015). In our study, the RWC values obtained from plants under drought stress showed that the transgenic lines retained less water than the non-transgenic plants (Table 1). The difference was significant for transgenic line PtrFBL1-13 at 4 days (P = 0.011) and for both lines at 6 days (P = 0.001) after the deprival of watering. This indicated that PtrFBL1 played a key role in the balance of plant growth and tolerance. Although the roles of TIR1 in many developmental processes in Arabidopsis have been well documented (Parry et al., 2009), the effects of its homolog PtrFBL1 in poplar on the stem growth and tolerance were first found in this study.


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 growth and drought tolerance of PtrFBL1 over-expressed poplars. (A) Phenotypic changes in stem growth of over-expressing PtrFBL1; (B) Relative expression for over-expressing PtrFBL1; (C) The height and diameters of non- and transgenic lines; (D,E) Phenotypic changes of the PtrFBL1 over-expressed plants after drought treatment for 6 days and the photos were taken 15 days after rewatering. Bars, 5 cm (A,D,E), *indicates significant difference at P < 0.05, and **indicates extremely significant difference at P < 0.01.
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Related In: Results  -  Collection

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Show All Figures
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Figure 6: The growth and drought tolerance of PtrFBL1 over-expressed poplars. (A) Phenotypic changes in stem growth of over-expressing PtrFBL1; (B) Relative expression for over-expressing PtrFBL1; (C) The height and diameters of non- and transgenic lines; (D,E) Phenotypic changes of the PtrFBL1 over-expressed plants after drought treatment for 6 days and the photos were taken 15 days after rewatering. Bars, 5 cm (A,D,E), *indicates significant difference at P < 0.05, and **indicates extremely significant difference at P < 0.01.
Mentions: To investigate the role of PtrFBL1 in stem development, we successfully generated 84K transgenic lines constitutively over-expressing PtrFBL1 under the control of the 35S promoter. Three representative transgenic lines with relative expression over 14-fold were used for further analysis (Figures 6A,B). We observed apparent phenotypic changes in height and diameter of the transgenic plants (Figures 6A,C), which were significantly higher than that of the non-transgenic controls (P = 0.015 and P = 0.006, respectively). However, we found that the transgenic plants exhibited decreased tolerance under drought treatment (Figures 6D,E). RWC was a measure of plant water status and used as a meaningful index of water stress tolerance (Negi et al., 2015). In our study, the RWC values obtained from plants under drought stress showed that the transgenic lines retained less water than the non-transgenic plants (Table 1). The difference was significant for transgenic line PtrFBL1-13 at 4 days (P = 0.011) and for both lines at 6 days (P = 0.001) after the deprival of watering. This indicated that PtrFBL1 played a key role in the balance of plant growth and tolerance. Although the roles of TIR1 in many developmental processes in Arabidopsis have been well documented (Parry et al., 2009), the effects of its homolog PtrFBL1 in poplar on the stem growth and tolerance were first found in this study.

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