title: TOPOISOMERASE1α Acts through Two Distinct Mechanisms to Regulate Stele and Columella Stem Cell Maintenance.
abstract: TOPOISOMERASE1 (TOP1), which releases DNA torsional stress generated during replication through its DNA relaxation activity, plays vital roles in animal and plant development. In Arabidopsis (Arabidopsis thaliana), TOP1 is encoded by two paralogous genes (TOP1α and TOP1β), of which TOP1α displays specific developmental functions that are critical for the maintenance of shoot and floral stem cells. Here, we show that maintenance of two different populations of root stem cells is also dependent on TOP1α-specific developmental functions, which are exerted through two distinct novel mechanisms. In the proximal root meristem, the DNA relaxation activity of TOP1α is critical to ensure genome integrity and survival of stele stem cells (SSCs). Loss of TOP1α function triggers DNA double-strand breaks in S-phase SSCs and results in their death, which can be partially reversed by the replenishment of SSCs mediated by ETHYLENE RESPONSE FACTOR115 In the quiescent center and root cap meristem, TOP1α is epistatic to RETINOBLASTOMA-RELATED (RBR) in the maintenance of undifferentiated state and the number of columella stem cells (CSCs). Loss of TOP1α function in either wild-type or RBR RNAi plants leads to differentiation of CSCs, whereas overexpression of TOP1α mimics and further enhances the effect of RBR reduction that increases the number of CSCs Taken together, these findings provide important mechanistic insights into understanding stem cell maintenance in plants.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China (Y.Z., L.Z., C.Z.);Department of Biological Sciences and NUS Centre for BioImaging Sciences, National University of Singapore, Singapore 117543 (J.H.H., X.G., J.X.); andInstituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain (J.M.P.-P.).
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China (Y.Z., L.Z., C.Z.);Department of Biological Sciences and NUS Centre for BioImaging Sciences, National University of Singapore, Singapore 117543 (J.H.H., X.G., J.X.); andInstituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain (J.M.P.-P.).
authors.forename: Lanlan
authors.initials: L
authors.lastname: Zheng
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China (Y.Z., L.Z., C.Z.);Department of Biological Sciences and NUS Centre for BioImaging Sciences, National University of Singapore, Singapore 117543 (J.H.H., X.G., J.X.); andInstituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain (J.M.P.-P.).
authors.forename: Jing Han
authors.initials: JH
authors.lastname: Hong
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China (Y.Z., L.Z., C.Z.);Department of Biological Sciences and NUS Centre for BioImaging Sciences, National University of Singapore, Singapore 117543 (J.H.H., X.G., J.X.); andInstituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain (J.M.P.-P.).
authors.forename: Ximing
authors.initials: X
authors.lastname: Gong
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China (Y.Z., L.Z., C.Z.);Department of Biological Sciences and NUS Centre for BioImaging Sciences, National University of Singapore, Singapore 117543 (J.H.H., X.G., J.X.); andInstituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain (J.M.P.-P.).
authors.forename: Chun
authors.initials: C
authors.lastname: Zhou
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China (Y.Z., L.Z., C.Z.);Department of Biological Sciences and NUS Centre for BioImaging Sciences, National University of Singapore, Singapore 117543 (J.H.H., X.G., J.X.); andInstituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain (J.M.P.-P.).
authors.forename: José Manuel
authors.identifier: 0000-0003-2848-4919
authors.initials: JM
authors.lastname: Pérez-Pérez
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China (Y.Z., L.Z., C.Z.);Department of Biological Sciences and NUS Centre for BioImaging Sciences, National University of Singapore, Singapore 117543 (J.H.H., X.G., J.X.); andInstituto de Bioingeniería, Universidad Miguel Hernández, 03202 Elche, Spain (J.M.P.-P.) dbsxj@nus.edu.sg.
authors.forename: Jian
authors.identifier: 0000-0001-6194-6316
authors.initials: J
authors.lastname: Xu
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002470:Cell Survival / Q000235:genetics; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D018519:Meristem / Q000235:genetics; D059828:Plant Cells / Q000502:physiology*; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C584817:ERF115 protein, Arabidopsis; D014157:Transcription Factors; D004264:DNA Topoisomerases, Type I; C469258:TOP1alpha protein, Arabidopsis; C469259:TOP1beta protein, Arabidopsis