title: Rootless with undetectable meristem 1 encodes a monocot-specific AUX/IAA protein that controls embryonic seminal and post-embryonic lateral root initiation in maize.
abstract: The maize (Zea mays L.) rum1-R (rootless with undetectable meristems 1-Reference) mutant does not initiate embryonic seminal roots and post-embryonic lateral roots at the primary root. Map-based cloning revealed that Rum1 encodes a 269 amino acid (aa) monocot-specific Aux/IAA protein. The rum1-R protein lacks 26 amino acids including the GWPPV degron sequence in domain II and part of the bipartite NLS (nuclear localization sequence). Significantly reduced lateral root density (approximately 35%) in heterozygous plants suggests that the rum1-R is a semi-dominant mutant. Overexpression of rum1-R under the control of the maize MSY (Methionine SYnthase) promoter supports this notion by displaying a reduced number of lateral roots (31-37%). Functional characterization suggests that Rum1 is auxin-inducible and encodes a protein that localizes to the nucleus. Moreover, RUM1 is unstable with a half life time of approximately 22 min while the mutant rum1-R protein is very stable. In vitro and in vivo experiments demonstrated an interaction of RUM1 with ZmARF25 and ZmARF34 (Z. mays AUXIN RESPONSE FACTOR 25 and 34). In summary, the presented data suggest that Rum1 encodes a canonical Aux/IAA protein that is required for the initiation of embryonic seminal and post-embryonic lateral root initiation in primary roots of maize.
authors.affiliation: Department of General Genetics, ZMBP, Center for Plant Molecular Biology, University of Tuebingen, 72076 Tuebingen, Germany.
authors.forename: Inga
authors.initials: I
authors.lastname: von Behrens
authors.forename: Mai
authors.initials: M
authors.lastname: Komatsu
authors.forename: Yanxiang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Berendzen
authors.forename: Xiaomu
authors.initials: X
authors.lastname: Niu
authors.forename: Hajime
authors.initials: H
authors.lastname: Sakai
authors.forename: Graziana
authors.initials: G
authors.lastname: Taramino
authors.forename: Frank
authors.initials: F
authors.lastname: Hochholdinger
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D018517:Plant Roots / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000737:chemistry / Q000235:genetics / Q000254:growth & development; D036226:Seedlings / Q000235:genetics / Q000254:growth & development; D020539:Sequence Analysis, Protein; D003313:Zea mays / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development
chemical_list: D010940:Plant Proteins