title: Expression of Bacillus thuringiensis cytolytic toxin (Cyt2Ca1) in citrus roots to control Diaprepes abbreviatus larvae.
abstract: Diaprepes abbreviatus (L.) is an important pest of citrus in the USA. Currently, no effective management strategies of D. abbreviatus exist in citriculture, and new methods of control are desperately sought. To protect citrus against D. abbreviatus a transgenic citrus rootstock expressing Bacillus thuringiensis Cyt2Ca1, an insect toxin protein, was developed using Agrobacterium-mediated transformation of 'Carrizo' citrange [Citrus sinensis (L) Osbeck Poncirus trifoliate (L) Raf]. The transgenic citrus root stock expressed the cytolytic toxin Cyt2Ca1 constitutively under the control of a 35S promoter in the transgenic Carrizo citrange trifoliate hybrid including the roots that are the food source of larval D. abbreviatus. The engineered citrus was screened by Western blot and RT-qPCR analyses for cyt2Ca1 and positive citrus identified. Citrus trees expressing different levels of cyt2Ca1 transcripts were identified (Groups A-C). High expression of the toxin in the leaves (109transcripts/ng RNA), however, retarded plant growth. The transgenic plants were grown in pots and the roots exposed to 3week old D. abbreviatus larvae using no-choice plant bioassays. Three cyt2Ca1 transgenic plants were identified that sustained less root damage belonging to Group B and C. One plant caused death to 43% of the larvae that fed on its roots expressed 8×106cyt2Ca1 transcripts/ng RNA. These results show, for the first time, that Cyt2Ca1 expressed in moderate amounts by the roots of citrus does not retard citrus growth and can protect it from larval D. abbreviatus.
authors.affiliation: Indian River Research and Education Center, University of Florida, Fort Pierce, FL 34945, USA.
authors.forename: Sulley Ben
authors.initials: SB
authors.lastname: Mahmoud
authors.affiliation: United States Horticultural Research Laboratory, United States Department of Agriculture, Agricultural Research Service, 2001 South Rock Road, Ft. Pierce, FL 34945, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Ramos
authors.affiliation: United States Horticultural Research Laboratory, United States Department of Agriculture, Agricultural Research Service, 2001 South Rock Road, Ft. Pierce, FL 34945, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Shatters
authors.affiliation: United States Horticultural Research Laboratory, United States Department of Agriculture, Agricultural Research Service, 2001 South Rock Road, Ft. Pierce, FL 34945, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Hall
authors.affiliation: United States Horticultural Research Laboratory, United States Department of Agriculture, Agricultural Research Service, 2001 South Rock Road, Ft. Pierce, FL 34945, USA.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Lapointe
authors.affiliation: United States Horticultural Research Laboratory, United States Department of Agriculture, Agricultural Research Service, 2001 South Rock Road, Ft. Pierce, FL 34945, USA.
authors.forename: Randall P
authors.initials: RP
authors.lastname: Niedz
authors.affiliation: Université de Toulouse, UPS, Institut de Recherche pour le Développement (IRD), UMR 152 Pharma-Dev, Faculté des Sciences Pharmaceutiques, F-31062 Toulouse cedex 09, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Rougé
authors.affiliation: Indian River Research and Education Center, University of Florida, Fort Pierce, FL 34945, USA.
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Cave
authors.affiliation: United States Horticultural Research Laboratory, United States Department of Agriculture, Agricultural Research Service, 2001 South Rock Road, Ft. Pierce, FL 34945, USA. Electronic address: dovborovsky@gmail.com.
authors.forename: Dov
authors.initials: D
authors.lastname: Borovsky
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics*; D002957:Citrus / Q000235:genetics* / Q000254:growth & development; D007814:Larva; D008958:Models, Molecular; D010572:Pest Control, Biological; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D018517:Plant Roots / Q000235:genetics* / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000254:growth & development; D048889:Weevils
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins
keywords: Diaprepes abbreviatus; Genetic transformation; Larval control; Root resistance; Transgenic citrus rootstock; cyt2Ca1