SEROLOGICAL IDENTIFICATION OF CITRUS TRISTEZA CLOSTEROVIRUS (CTV) AND MOLECULAR CHARACTERIZATION OF ITS COAT PROTEIN GENE

Abstract

Citrus Tristeza Closterovirus (CTV) is ranked as one of the most important citrus diseases in the world and it is an emerging problem in Pakistan. Citrus composite samples were collected from Islamabad and subjected to Double Antibody Sandwich Enzyme Linked Immunosorbant Assay (DAS-ELISA). On the basis of DAS-ELISA results, disease incidence of CTV was 33% (OD _405nm 0.908-2.524) and increased up to 61% (OD _405nm 0.916-2.620) during 2009 and 2010 respectively. Plants grafted with CTV infected samples exhibiting no symptoms but showed their reaction against ELISA (OD _405nm 1.184-1.286). Designed coat protein (CP) gene specific sense and antisense primers successfully amplified a 0.6 kb fragment through Polymerase Chain Reaction (PCR) assay. A few citrus plants those exhibiting no reaction in ELISA were positive in PCR.