Citrus tristeza virus-based RNA-interference (RNAi) vector and its potential in combating citrus Huanglongbing (HLB)

Citrus tristeza virus (CTV) is the most important virus disease of citrus in the world. CTV causes death of trees on sour orange rootstock and/or stem pitting of scions regardless of rootstock which results in trees of low vigor, reduced yield with reduction in size and quality of fruit. The purpose of this project was to produce monoclonal antibodies (MABs) to CTV coat protein (CP), develop single domain antibodies (dAbs) or Fab fragments which neutralize the infection by binding to the virus, and to produce transformed plants which express the dAbs. The objectives of this research have been met and putative transgenic tobacco and citrus plants have been developed. These putative transgenic plants are presently undergoing evaluation to determine the level of dAbs expression and to determine their resistance to CTV. Additionally, the CTV genome has been sequenced and the CP gene of several biologically characterized CTV strains molecular characterized. This has indicated a correlation between CP sequence homology and biological activity, and the finding of DI RNAs associated with some CTV strains. Several MABs have been produced which enable broad spectrum identification of CTV strains while other MABs enable differentiation between mild and severe strains. The use of selected MAbs and determination of the CP gene sequence has enabled predictions of biological activities of unknown CTV isolates. The epitopes of two MABs, one reacting selectively with severe CTV strains and the other reacting with all strains, have been characterized at the molecular level.

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Evaluation of the protective capacity of new mild Citrus tristeza virus (CTV) isolates selected for a preimmunization program

Scientia Agricola ◽

10.1590/s0103-90162013000200009 ◽

2013 ◽

Vol 70 (2) ◽

pp. 116-124 ◽

Cited By ~ 7

Author(s):

Carlos Alexandre Zanutto ◽

Maria Júlia Corazza ◽

William Mário de Carvalho Nunes ◽

Gerd Walter Müller

Keyword(s):

Citrus Tristeza Virus ◽

Protective Capacity ◽

Tristeza Virus ◽

Citrus Tristeza

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Eliminação de vírus do complexo sorose dos citros por microenxertia associada a termoterapia

Fitopatologia Brasileira ◽

10.1590/s0100-41582002000300012 ◽

2002 ◽

Vol 27 (3) ◽

pp. 306-308 ◽

Cited By ~ 8

Author(s):

SÉRGIO A. CARVALHO ◽

FRANCISCA A. SANTOS ◽

MARCOS A. MACHADO

Keyword(s):

Citrus Tristeza Virus ◽

Citrus Exocortis Viroid ◽

Tristeza Virus ◽

Citrus Tristeza

A microenxertia de ápices caulinares tem sido utilizada com 100% de sucesso na eliminação do vírus da tristeza (Citrus tristeza virus) e dos viróides da exocorte (Citrus exocortis viroid - CEVd) e cachexia-xiloporose de materiais do Banco Ativo de Germoplasma de Citros do Centro de Citricultura Sylvio Moreira CCSM-IAC. Para o complexo da sorose, entretanto, esta técnica tem apresentado somente 60% de eficiência, indicando a necessidade de sua associação com termoterapia para garantir a eliminação viral. Para tanto, mudas originadas de borbulhas infetadas com sorose foram mantidas em câmara climática com 16 h de luz a 38 ºC e 8 h no escuro a 32 ºC e utilizadas para a obtenção dos ápices caulinares empregados na microenxertia. Após o pegamento, o conjunto micro porta-enxerto e brotação foi sobre-enxertado em limoeiro (Citrus limonia) 'Cravo' com sete meses de idade e mantido em condições de casa de vegetação. Clones de laranjeiras doces (Citrus sinsensis) 'Lima', 'Rubi', 'Piralima', 'Salustiana', 'João Nunes', 'Rosa' e 'Pêra Caire' tratados desta maneira, comprovaram eficiência de 100% de eliminação do complexo sorose, conforme indexação realizada empregando-se laranjeira 'Do Céu' como planta indicadora.

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