title: The Arabidopsis Rho of plants GTPase AtROP6 functions in developmental and pathogen response pathways.
abstract: How plants coordinate developmental processes and environmental stress responses is a pressing question. Here, we show that Arabidopsis (Arabidopsis thaliana) Rho of Plants6 (AtROP6) integrates developmental and pathogen response signaling. AtROP6 expression is induced by auxin and detected in the root meristem, lateral root initials, and leaf hydathodes. Plants expressing a dominant negative AtROP6 (rop6(DN)) under the regulation of its endogenous promoter are small and have multiple inflorescence stems, twisted leaves, deformed leaf epidermis pavement cells, and differentially organized cytoskeleton. Microarray analyses of rop6(DN) plants revealed that major changes in gene expression are associated with constitutive salicylic acid (SA)-mediated defense responses. In agreement, their free and total SA levels resembled those of wild-type plants inoculated with a virulent powdery mildew pathogen. The constitutive SA-associated response in rop6(DN) was suppressed in mutant backgrounds defective in SA signaling (nonexpresser of PR genes1 [npr1]) or biosynthesis (salicylic acid induction deficient2 [sid2]). However, the rop6(DN) npr1 and rop6(DN) sid2 double mutants retained the aberrant developmental phenotypes, indicating that the constitutive SA response can be uncoupled from ROP function(s) in development. rop6(DN) plants exhibited enhanced preinvasive defense responses to a host-adapted virulent powdery mildew fungus but were impaired in preinvasive defenses upon inoculation with a nonadapted powdery mildew. The host-adapted powdery mildew had a reduced reproductive fitness on rop6(DN) plants, which was retained in mutant backgrounds defective in SA biosynthesis or signaling. Our findings indicate that both the morphological aberrations and altered sensitivity to powdery mildews of rop6(DN) plants result from perturbations that are independent from the SA-associated response. These perturbations uncouple SA-dependent defense signaling from disease resistance execution.
authors: Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel.
authors: Limor
authors: L
authors: Poraty-Gavra
authors: Philip
authors: P
authors: Zimmermann
authors: Sabine
authors: S
authors: Haigis
authors: Pawel
authors: P
authors: Bednarek
authors: Ora
authors: O
authors: Hazak
authors: Oksana Rogovoy
authors: OR
authors: Stelmakh
authors: Einat
authors: E
authors: Sadot
authors: Paul
authors: P
authors: Schulze-Lefert
authors: Wilhelm
authors: W
authors: Gruissem
authors: Shaul
authors: S
authors: Yalovsky
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D005658:Fungi / Q000187:drug effects / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D019441:Plant Epidermis / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D018520:Plant Shoots / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D020156:Salicylic Acid / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology
chemical_list: D029681:Arabidopsis Proteins; C518506:ROP6 protein, Arabidopsis; D049452:Green Fluorescent Proteins; D020559:Monomeric GTP-Binding Proteins; D020156:Salicylic Acid