title: Plant Rac-like GTPases are activated by auxin and mediate auxin-responsive gene expression.
abstract: The auxin indole-3-acetic acid is a key plant hormone essential for a broad range of growth and developmental processes. Here, we show that auxin activates Rac-like GTPases (referred to as Rac/Rop GTPases), and they in turn stimulate auxin-responsive gene expression. In particular, we show that overexpressing a wild-type tobacco Rac/Rop GTPase, NtRac1, and its constitutively active mutant form activates auxin-responsive gene expression. On the other hand, overexpressing dominant-negative NtRac1 and Rac-negative regulators, or reducing the endogenous NtRac1 level, suppresses auxin-induced gene expression. Furthermore, overexpression of NtRac1 activity or suppression of its expression in transgenic seedlings induces phenotypes that are similar to auxin-related defects. Together, our results show that a subset of plant Rac/Rop GTPases functions in mediating the auxin signal to downstream responsive genes.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003, USA.
authors.forename: Li-zhen
authors.initials: LZ
authors.lastname: Tao
authors.forename: Alice Y
authors.initials: AY
authors.lastname: Cheung
authors.forename: Hen-ming
authors.initials: HM
authors.lastname: Wu
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010641:Phenotype; D030821:Plants, Genetically Modified; D015398:Signal Transduction / Q000187:drug effects; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D020744:rac GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; C030737:indoleacetic acid; C459444:RopGAP4 protein, Arabidopsis; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins