Detection and characterization of Citrus tristeza virus in national germplasm collection in Afghanistan

Rejuvenation of the horticulture industry is a government priority in Afghanistan. Whit the same purpose the EC supported programmes that specifically focus on increase access to improved and appropriate planting materials in order to increase quantity and quality of more competitive horticultural products. Establishment of a biotechnology laboratory and its services in quality control and management of the horticulture input chains were considerate an essential support to horticulture sector development. This laboratory (nome lab?) started screening the health status of the Afghan Germplasm National Collection in order to ensure multiplication of not only the best selected varieties or ecotypes, but also to avoid production and distribution of virus-infected fruit trees. During survey activity on citrus National collection experimental farm in Jalalabad, plants from accessions showing vein flecking, yellowing and plant decline symptoms were sampled and analyzed by ELISA test. Four accessions: Kumquat cv. Margarita, Orange cv. Mahali, Mandarin Group cv. Fruter and Rough lemon cv. Mahali resulted infected by Citrus tristeza virus (CTV). CTV, known to be transmitted by aphids, causes a serious and dangerous disease that can rapidly spread and destroy orchards. In order to preserve citrus national collection from CTV infection a deep study on identified isolates characterization has been undertaken. A 655 nucleotides long fragment, corresponding to the major coat protein gene, has been amplified by RT-PCR from all ELISA-positive samples. Preliminary sequence analysis revealed identity ranging from 91 to 100% within Afghan CTV isolates and high similarity of those with GenBank isolates from Angola, India and USA.