title: The initiation of lateral roots in the primary roots of maize (Zea mays L.) implies a reactivation of cell proliferation in a group of founder pericycle cells.
abstract: The initiation of lateral roots (LRs) has generally been viewed as a reactivation of proliferative activity in pericycle cells that are committed to initiate primordia. However, it is also possible that pericycle founder cells that initiate LRs never cease proliferative activity but rather are displaced to the most distal root zones while undertaking successive stages of LR initiation. In this study, we tested these two alternative hypotheses by examining the incorporation of 5-bromo-2'-deoxyuridine (BrdU) into the DNA of meristematic root cells of Zea mays. According to the values for the length of the cell cycle and values for cell displacement along the maize root, our results strongly suggest that pericycle cells that initiate LR primordia ceased proliferative activity upon exiting the meristematic zone. This finding is supported by the existence of a root zone between 4 and 20mm from the root cap junction, in which neither mitotic cells nor labelled nuclei were observed in phloem pericycle cells.
authors.affiliation: Departamento de Hortofruticultura, Centro de Investigación La Orden (CICYTEX), Gobierno de Extremadura, 06187 Badajoz, Spain.
authors.forename: M Victoria
authors.initials: MV
authors.lastname: Alarcón
authors.affiliation: Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain.
authors.forename: Pedro G
authors.initials: PG
authors.lastname: Lloret
authors.affiliation: Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain.
authors.forename: Gervasio
authors.initials: G
authors.lastname: Martín-Partido
authors.affiliation: Departamento de Biología Vegetal, Ecología y Ciencias de la Tierra, Universidad de Extremadura, 06007 Badajoz, Spain. Electronic address: salguero@unex.es.
authors.forename: Julio
authors.initials: J
authors.lastname: Salguero
mesh_terms: D002455:Cell Division; D049109:Cell Proliferation; D018519:Meristem / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D052585:Phloem / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D003313:Zea mays / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000502:physiology
keywords: 5-Bromo-2′-deoxyuridine; Founder cell; Lateral root initiation; Pericycle