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Doctoral Thesis
DOI
10.11606/T.64.2009.tde-30092009-110219
Document
Author
Full name
Liliane Cristina Liborio Stipp
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2009
Supervisor
Committee
Martinelli, Adriana Pinheiro (President)
Harakava, Ricardo
Melo, Arlete Marchi Tavares de
Monteiro, Mariza
Rezende, Jorge Alberto Marques
Title in Portuguese
Transformação genética de abobrinha-de-moita e melancia para resistência ao Papaya ringspot virus - type Watermelon e ao Zucchini yellow mosaic virus
Keywords in Portuguese
Agrobacterium tumefaciens
Citrullus lanatus
Cucurbita pepo
Plantas transgênicas
Potyvirus
Abstract in Portuguese
No Brasil, doenças causadas pelo Papaya ringspot virus - type Watermelon (PRSV-W) e Zucchini yellow mosaic virus (ZYMV) reduzem a produção e a qualidade dos frutos de abobrinha-de-moita (Cucurbita pepo) e melancia (Citrullus lanatus), assim como em outras cucurbitáceas. O objetivo deste trabalho foi a obtenção de plantas transgênicas de abobrinha-de-moita e melancia resistentes ao PRSV-W e ao ZYMV. Um sistema eficiente de regeneração in vitro é necessário para a obtenção de plantas transgênicas. O sistema de organogênese in vitro de abobrinha-de-moita foi desenvolvido utilizando como explantes a região basal do cotilédone e um segmento do hipocótilo obtidos a partir de sementes germinadas in vitro. Os explantes foram cultivados em meio de cultura MS (MURASHIGE; SKOOG, 1962), suplementado com diferentes concentrações de BAP (benzilaminopurina). A indução de gemas adventícias foi mais eficiente nas concentrações de 1,0 e 1,25 mg/L de BAP. Este protocolo foi usado para regenerar plantas em experimentos de transformação genética de abobrinha-de-moita cv. Caserta e melancia cv. Crimson Sweet, via Agrobacterium tumefaciens. O vetor binário pCAMBIA2201, contendo fragmentos dos genes da proteína capsidial do ZYMV e do PRSV-W, numa construção gênica do tipo hairpin e o gene de seleção nptII, sob controle do promotor 35S, foi usado nos experimentos de transformação genética. Após 2 dias de co-cultivo, em meio de cultura MS, suplementado com BAP (1 mg/L), os explantes foram transferidos para meio de cultura de seleção, suplementado com BAP (1 mg/L), timentin (400 mg/L) e canamicina (100 mg/L) e cultivados por 3 a 4 semanas, sob fotoperíodo de 16 horas de luz. Plantas regeneradas foram analisadas por PCR, usando primers específicos para detecção dos fragmentos dos genes da proteína capsidial do PRSV-W e ZYMV. Foram utilizados 1050 explantes de abobrinha-de-moita e de 973 explantes de melancia, resultando em 36 e 59 plantas PCR positivas, respectivamente. A eficiência de transformação foi de 3,4% para abobrinha-de-moita e 6,1% para melancia. Plantas PCR positivas foram aclimatizadas, gradualmente, em sala de luz e transferidas para casa-de-vegetação. Pela análise de Southern blot foi confirmada a integração dos fragmentos dos genes da proteína capsidial do ZYMV e PRSV-W em 3 plantas de abobrinha-de-moita. Depois de desenvolvidas, flores femininas foram polinizadas manualmente e sementes foram coletadas de frutos maduros. Plantas R1 de abobrinha-de-moita e melancia foram inoculadas com o PRSV-W e o ZYMV por meio de Myzus nicotianae virulíferos. Não foram identificadas, até o momento, plantas resistentes aos patógenos em estudo
Title in English
Genetic transformation of zucchini squash and watermelon for resistance to Papaya ringspot virus - type W and Zucchini yellow mosaic virus
Keywords in English
Agrobacterium tumefaciens
Citrullus lanatus
Cucurbita pepo
Potyvirus
Transgenic plants
Abstract in English
Diseases caused by the potyviruses Papaya ringspot virus - type Watermelon (PRSV-W) and Zucchini yellow mosaic virus (ZYMV) significantly reduce the yield and fruit quality of zucchini squash (Cucurbita pepo), watermelon (Citrullus lanatus), as well as other cucurbit crops in Brazil. The purpose of this work was to obtain zucchini squash and watermelon transgenic plants resistant to PRSV-W and ZYMV. An efficient in vitro regeneration system which can be associated with the protocol is necessary to obtain transgenic plants. In vitro organogenesis system was successfully developed using comprised of distal region of hypocotyl and the base of cotyledon of a germinated seed. The explants were cultured in MS medium (MURASHIGE; SKOOG, 1962), supplemented with different concentraction of BAP (benzylaminopurine). The induction of adventitious buds was more efficient at concentrations of 1.0 and 1.25 mg.L-1 BAP. This protocol was used to regenerate plants from genetic transformation experiments with zucchini squash cv. Caserta and watermelon cv. Crimson Sweet via Agrobacterium tumefaciens. For transformation, the binary vector pCAMBIA 2201, containing sequences of the coat protein coding regions of ZYMV and PRSV-W in a hairpin construct and the nptII gene, driven by 35S promoter was used. After 2 days of co-culture in MS medium supplemented with BAP (1.0 mg.L-1), explants were transferred to the MS selection culture medium, supplemented with BAP (1.0 mg.L-1), timentin (400 mg.L-1) and kanamycin (100 mg.L-1), and incubated for 3 to 4 weeks at 27 oC, under 16 h photoperiod. Regenerated plants were analyzed by PCR, using specific pairs of primers for the detection of the coat protein gene segments of PRSV-W and ZYMV. A total of 1,050 zucchini squash and 973 watermelon explants were used in the transformation experiments, resulting in 36 and 59 PCR positive plants, respectively. The genetic transformation efficiency was 3.4% for zucchini squash and 6.1% for watermelon. The PCR positive plants were slowly acclimatized in the culture room and transferred to the greenhouse for further growth. Southern blot analysis confirmed the genome integration of the the ZYMV and PRSV-W coat protein gene fragments in three zucchini squash plants which survived the acclimatization step. Later in development, female flowers were were manually pollinated and seeds were collected from mature fruits. R1 transgenic zucchini squash and watermelon plants were inoculated with PRSV-W and ZYMV by means of viruliferous Myzus nicotianae. Resistant plants were not yet observed among the R1 plants available
 
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Publishing Date
2009-10-14
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • Stipp, Liliane Cristina Libório, Monteiro-Hara, Alessandra Cristina Boffino de Almeida, and MENDES, B. M. J. In vitro organogenesis of zucchini squash cv. Caserta. Horticultura Brasileira , 2012, vol. 30, p. 274-278.
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