title: Overexpression of the AtSHI gene in poinsettia, Euphorbia pulcherrima, results in compact plants.
abstract: Euphorbia pulcherrima, poinsettia, is a non-food and non-feed vegetatively propagated ornamental plant. Appropriate plant height is one of the most important traits in poinsettia production and is commonly achieved by application of chemical growth retardants. To produce compact poinsettia plants with desirable height and reduce the utilization of growth retardants, the Arabidopsis SHORT INTERNODE (AtSHI) gene controlled by the cauliflower mosaic virus 35S promoter was introduced into poinsettia by Agrobacterium-mediated transformation. Three independent transgenic lines were produced and stable integration of transgene was verified by PCR and Southern blot analysis. Reduced plant height (21-52%) and internode lengths (31-49%) were obtained in the transgenic lines compared to control plants. This correlates positively with the AtSHI transcript levels, with the highest levels in the most dwarfed transgenic line (TL1). The indole-3-acetic acid (IAA) content appeared lower (11-31% reduction) in the transgenic lines compared to the wild type (WT) controls, with the lowest level (31% reduction) in TL1. Total internode numbers, bract numbers and bract area were significantly reduced in all transgenic lines in comparison with the WT controls. Only TL1 showed significantly lower plant diameter, total leaf area and total dry weight, whereas none of the AtSHI expressing lines showed altered timing of flower initiation, cyathia abscission or bract necrosis. This study demonstrated that introduction of the AtSHI gene into poinsettia by genetic engineering can be an effective approach in controlling plant height without negatively affecting flowering time. This can help to reduce or avoid the use of toxic growth retardants of environmental and human health concern. This is the first report that AtSHI gene was overexpressed in poinsettia and transgenic poinsettia plants with compact growth were produced.
authors: Bioforsk-Norwegian Institute for Agricultural and Environmental Research, Ås, Norway.
authors: M Ashraful
authors: MA
authors: Islam
authors: Henrik
authors: H
authors: Lütken
authors: Sissel
authors: S
authors: Haugslien
authors: Dag-Ragnar
authors: DR
authors: Blystad
authors: Sissel
authors: S
authors: Torre
authors: Jakub
authors: J
authors: Rolcik
authors: Søren K
authors: SK
authors: Rasmussen
authors: Jorunn E
authors: JE
authors: Olsen
authors: Jihong Liu
authors: JL
authors: Clarke
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics*; D017796:Caulimovirus / Q000235:genetics*; D028481:Euphorbia / Q000033:anatomy & histology / Q000235:genetics*; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics; D015870:Gene Expression; D017343:Genes, Plant; D018525:Germination / Q000235:genetics; D007210:Indoleacetic Acids / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000033:anatomy & histology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D014170:Transformation, Genetic; D019076:Transgenes
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D012333:RNA, Messenger; D014157:Transcription Factors; C120562:short internodes protein, Arabidopsis; C030737:indoleacetic acid