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Doctoral Thesis
DOI
Document
Author
Full name
Janaynna Magalhães Barbosa-Mendes
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2007
Supervisor
Committee
Camargo, Luis Eduardo Aranha (President)
Guzzo, Sylvia Dias
Harakava, Ricardo
Mourão Filho, Francisco de Assis Alves
Rezende, Jorge Alberto Marques
Title in Portuguese
Transformação genética de laranja doce (Citrus sinensis L. Osbeck) com o gene hrpN (harpina) e avaliação da resistência ao cancro cítrico (Xanthomonas axonopodis pv. citri)
Keywords in Portuguese
Cancro – Doença de planta
Engenharia genética
Genes
Laranja
Resistência genética
Xanthomonas
Abstract in Portuguese
A indústria dos citros é de grande importância econômica e social para o Brasil, que é considerado o maior produtor e exportador de suco concentrado de laranja do mundo. Porém, sérios problemas relacionados a doenças têm afetado a produção e qualidade dos citros. Com o desenvolvimento da engenharia genética e a clonagem de genes relacionados à resistência a doenças em plantas, a transformação genética têm se mostrado uma ferramenta auxiliar a programas de melhoramento genético de citros. O objetivo deste trabalho foi a obtenção de plantas transgênicas de laranja doce das variedades ‘Hamlin’, ‘Valência, ‘Natal’ e ‘Pêra’ expressando o gene hrpN, sob o controle do promotor Pgst1, induzível pelo patógeno. A avaliação da resposta de plantas transgênicas da variedade ‘Hamlin’ contra o agente causal do cancro cítrico, a bactéria Xanthomonas axonopodis pv. citri, também foi realizada. Segmentos de epicótilo foram transformados via Agrobacterium tumefaciens, e selecionados em meio de cultura suplementado com canamicina ou gentamicina. A transformação genética foi confirmada por PCR e Southern blot. A transcrição do gene foi avaliada por RT-PCR e a produção da proteína harpina foi analisada por western blot. A eficiência de transformação variou de 2,7 e 6,2% de acordo com a variedade de laranja. Algumas linhagens de plantas transgênicas apresentaram desenvolvimento anormal, não permitindo a realização da análise por Southern blot nem a multiplicação por enxertia. Plantas de laranja ‘Hamlin’ foram propagadas por enxertia e avaliadas para resistência a Xanthomonas axonopodis pv. citri. Todas as linhagens apresentaram redução na severidade dos sintomas causados pela bactéria X. axonopodis pv. citri, avaliados 30 dias após a inoculação.
Title in English
Sweet orange (Citrus sinensis L. Osbeck) genetic transformation with the hrpN gene (harpin) and evaluation for citrus canker (Xanthomonas axonopodis pv. citri) resistance
Keywords in English
hrpN gene
Xanthomonas axonopodis pv. citri
Disease resistance
Genetic transformation
Inducible promotor
Sweet orange
Abstract in English
The citrus industry has a great economic and social importance for Brazil, which is considered largest producer and orange juice exporter in the world. However, serious problems related to pathogens have affected citrus production and quality. With the development of genetic engineering and the characterization of genes related with plant disease resistance, the genetic transformation became an important tool in citrus breeding programs. The objective of this work was the production of transgenic plants of four sweet orange cultivars ‘Hamlin’, ‘Valencia’, ‘Natal’ and ‘Pera’ expressing hrpN gene under the control of Pgst1 inducible promoter. The evaluation of ‘Hamlin’ sweet orange transgenic plants infected with the causal agent of citrus canker, Xanthomonas axonopodis pv. citri was carry out. Epicotyl segments were inoculated with Agrobacterium tumefaciens, and selected in a culture medium supplemented with kanamycin or gentamycin. The genetic transformation was confirmed by PCR and Southern blot analysis. The gene transcription was evaluated by RT-PCR and the production of harpin protein was detected by western blot. The genetic transformation efficiency varied from 2,7% to 6,2% depending on the cultivar. Some transgenic lines had abnormal development, not allowing performing Southern blot analysis or multiplication by grafting. Plants of ‘Hamlin’ sweet orange were propagated by grafting and evaluated for Xanthomonas axonopodis pv. citri resistance. All tested plants presented reduction in the severity of the symptoms caused by bacterium X. axonopodis pv. citri 30 days after the inoculation.
 
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JanaynnaMendes.pdf (1.17 Mbytes)
Publishing Date
2007-05-23
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • BARBOSA, Janaynna Magalhães, et al. Genetic transformation of Citrus sinensis cv. Hamlin with hrpN gene from Erwinia amylovora and evaluation of the transgenic lines for resistance to citrus canker [doi:10.1016/j.scienta.2009.04.001]. Scientia Horticulturae [online], 2009, vol. 122, p. 109-115.
  • BARBOSA-MENDES, Janaynna Magalhães, et al. Genetic transformation of Citrus sinensis cv. Hamlin with hrpN gene from Erwinia amylovora and evaluation of the transgenic lines for resistance to citrus canker [doi:10.1016/j.scienta.2009.04.001]. Scientia Horticulturae [online], 2009, vol. 122, n. 1, p. 109-115.
  • CARDOSO, Suane Coutinho, et al. Transgenic Sweet Orange (Citrus sinensis L. Osbeck) Expressing the attacin A Gene for Resistance to Xanthomonas citri subsp. citri [doi:10.1007/s11105-009-0141-0]. Plant Molecular Biology Reporter [online], 2010, vol. 28, n. 2, p. 185-192.
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