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ELIMINATION OF CITRUS TRISTEZA CLOSTEROVIRUS FROM CITRUS BUD-WOOD THROUGH THERMOTHERAPY

MUHAMMAD ARIF*, MUHAMMAD IBRAHIM, ATTIQUE AHMAD AND SHER HASSAN

Abstract: Citrus tristeza closterovirus (CTV) was eliminated from citrus bud-wood through thermotherapy in temperature controlled chamber (TCC). Three citrus species, sweet orange (Citrus sinensis), sour orange (C. aurantium) and Eureka lemon were mechanically and graft inoculated with CTV. The inoculated plants were indexed by double antibody sandwich-enzyme-linked immuno-sorbent assay (DAS-ELISA) to ensure the infection of the test plants. CTV was successfully eliminated from citrus bud-wood by incubating citrus germplasm at 35/30°C (day/night) for two weeks, followed by 40/35°C for another one week in preconditioning and then same germplasm was incubated at higher temperature 50/40°C for one week in TCC. CTV was not detected by DAS-ELISA or back inoculation of leaf extracts and graft inoculation on diagnostic plant species 3-4 months after inoculation. However, at higher temperature (50/40°C) treatment in TCC, 50% of plants were lost during one week of incubation. The plants kept at 50/40°C without preconditioning (35/30°C for two weeks, followed by 40/35°C for another one week) did not survive at higher temperature in TCC. CTV was completely eliminated from citrus plants after a week incubation period at 50/40°C.
 

Department of Plant Pathology, NWFP Agricultural University, Peshawar, Pakistan.
Dr. Muhammad Arif, Phone: +92 91 921 6552, Fax: +92 91 921 6520
Corresponding Author: arifmpk@yahoo.com or arifmpk64@hotmail.com