MOLECULAR CHARACTERIZATION AND CONSTRUCTION OF AN INFECTIOUS CLONE OF A NEW STRAIN OF TOMATO YELLOW LEAF CURL VIRUS IN SOUTHERN IRAN

Complete nucleotide sequence of an infectious cloned DNA of Tomato yellow leaf curl virus from Abadeh (TYLCV-[Ab]) was determined and found to be comprised of 2782 nucleotides. This isolate shares 95% sequence identity with an Israeli isolate of TYLCV and is considered as a new strain of TYLCV from Iran. In addition to Abadeh, the same virus was detected in naturally infected tomato field samples in Firouzabad, Boushehr and Yasouj. It seems that the TYLCV-[Ab] is a major component of tomato leaf curl disease in southern Iran. A subgenomic DNA, about one third the size of the viral genome, was also detected in naturally infected tomato plants. A partial dimeric (1.5 mer) TYLCV-[Ab] DNA clone was constructed in a binary vector and used to agroinoculate tomato (Solanum lycopersicum cv. Grosse Lisse) and tobacco (Nicotiana tabacum cv. Turkish) plants. Typical yellowing and leaf curl symptoms were observed on tomato, while tobacco appeared to be a symptomless host of the virus. The viral DNA was detected in newly emerging leaves of infected tomato and tobacco plants, showing that the single DNA component of TYLCV-[Ab] is sufficient for infectivity. Both molecular analysis and symptomatology indicate that this isolate is a severe strain of TYLCV.