title: Uncovering DELLA-Independent Gibberellin Responses by Characterizing New Tomato procera Mutants.
abstract: Gibberellin (GA) regulates plant development primarily by triggering the degradation/deactivation of the DELLA proteins. However, it remains unclear whether all GA responses are regulated by DELLAs. Tomato (Solanum lycopersicum) has a single DELLA gene named PROCERA (PRO), and its recessive pro allele exhibits constitutive GA activity but retains responsiveness to external GA. In the loss-of-function mutant pro(ΔGRAS), all examined GA developmental responses were considerably enhanced relative to pro and a defect in seed desiccation tolerance was uncovered. As pro, but not pro(ΔGRAS), elongation was promoted by GA treatment, pro may retain residual DELLA activity. In agreement with homeostatic feedback regulation of the GA biosynthetic pathway, we found that GA20oxidase1 expression was suppressed in pro(ΔGRAS) and was not affected by exogenous GA3. In contrast, expression of GA2oxidase4 was not affected by the elevated GA signaling in pro(ΔGRAS) but was strongly induced by exogenous GA3. Since a similar response was found in Arabidopsis thaliana plants with impaired activity of all five DELLA genes, we suggest that homeostatic GA responses are regulated by both DELLA-dependent and -independent pathways. Transcriptome analysis of GA-treated pro(ΔGRAS) leaves suggests that 5% of all GA-regulated genes in tomato are DELLA independent.
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Sivan
authors.initials: S
authors.lastname: Livne
authors.affiliation: Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108.
authors.forename: Vai S
authors.initials: VS
authors.lastname: Lor
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Ido
authors.initials: I
authors.lastname: Nir
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Natanella
authors.initials: N
authors.lastname: Eliaz
authors.affiliation: Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Asaph
authors.initials: A
authors.lastname: Aharoni
authors.affiliation: Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Olszewski
authors.affiliation: Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Eshed
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel david.weiss@mail.huji.ac.il.
authors.forename: David
authors.initials: D
authors.lastname: Weiss
mesh_terms: D000040:Abscisic Acid / Q000502:physiology; D025461:Feedback, Physiological; D017343:Genes, Plant / Q000502:physiology; D005875:Gibberellins / Q000502:physiology*; D018551:Solanum lycopersicum / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D010937:Plant Growth Regulators / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D012639:Seeds / Q000254:growth & development / Q000502:physiology; D059467:Transcriptome
chemical_list: D005875:Gibberellins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D000040:Abscisic Acid