title: Auxins differentially regulate root system architecture and cell cycle protein levels in maize seedlings.
abstract: Maize (Zea mays) root system architecture has a complex organization, with adventitious and lateral roots determining its overall absorptive capacity. To generate basic information about the earlier stages of root development, we compared the post-embryonic growth of maize seedlings germinated in water-embedded cotton beds with that of plants obtained from embryonic axes cultivated in liquid medium. In addition, the effect of four different auxins, namely indole-3-acetic acid (IAA), 1-naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA) and 2,4-dichlorophenoxyacetic acid (2,4-D) on root architecture and levels of the heat shock protein HSP101 and the cell cycle proteins CKS1, CYCA1 and CDKA1 were analyzed. Our data show that during the first days after germination, maize seedlings develop several root types with a simultaneous and/or continuous growth. The post-embryonic root development started with the formation of the primary root (PR) and seminal scutellar roots (SSR) and then continued with the formation of adventitious crown roots (CR), brace roots (BR) and lateral roots (LR). Auxins affected root architecture in a dose-response fashion; whereas NAA and IBA mostly stimulated crown root formation, 2,4-D showed a strong repressing effect on growth. The levels of HSP101, CKS1, CYCA1 and CDKA in root and leaf tissues were differentially affected by auxins and interestingly, HSP101 registered an auxin-inducible and root specific expression pattern. Taken together, our results show the timing of early branching patterns of maize and indicate that auxins regulate root development likely through modulation of the HSP101 and cell cycle proteins.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio A-1', Ciudad Universitaria Morelia, Morelia 58030, Michoacán, Mexico.
authors.forename: Enrique
authors.initials: E
authors.lastname: Martínez-de la Cruz
authors.affiliation: Departamento de Bioquímica, Facultad de Química, UNAM, Ciudad Universitaria, México DF C.P. 04510, Mexico.
authors.forename: Elpidio
authors.initials: E
authors.lastname: García-Ramírez
authors.affiliation: Departamento de Bioquímica, Facultad de Química, UNAM, Ciudad Universitaria, México DF C.P. 04510, Mexico.
authors.forename: Jorge M
authors.initials: JM
authors.lastname: Vázquez-Ramos
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio A-1', Ciudad Universitaria Morelia, Morelia 58030, Michoacán, Mexico. Electronic address: delacruz@umich.mx.
authors.forename: Homero
authors.initials: H
authors.lastname: Reyes de la Cruz
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio A-1', Ciudad Universitaria Morelia, Morelia 58030, Michoacán, Mexico. Electronic address: joselopezbucio@yahoo.com.mx.
authors.forename: José
authors.initials: J
authors.lastname: López-Bucio
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000494:pharmacology*; D063245:Plant Development / Q000187:drug effects; D010940:Plant Proteins / Q000378:metabolism*; D018517:Plant Roots / Q000033:anatomy & histology* / Q000187:drug effects; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism*; D003313:Zea mays / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D007210:Indoleacetic Acids; D010940:Plant Proteins
keywords: Auxins; Cell cycle; Cyclins; Maize; Root development