title: A Populus TIR1 gene family survey reveals differential expression patterns and responses to 1-naphthaleneacetic acid and stress treatments.
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.
authors.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.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Shu
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Yingli
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Houjun
authors.initials: H
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Shutang
authors.initials: S
authors.lastname: Zhao
authors.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.
authors.forename: Mengzhu
authors.initials: M
authors.lastname: Lu
keywords: FBL family; NAA; Populus; expression; phylogenetic analysis; stress responses