Begomoviruses associated with yellow leaf curl disease of tomato in Iran

The occurrence of Tomato yellow leaf curl virus (TYLCV; genus Begomovirus, family Geminiviridae) in the major tomato-growing areas of Iran was determined using TAS-ELISA and PCR. The nucleotide sequences of the coat protein (CP) gene and intergenic region (IR) of eight Iranian isolates were determined. CP nucleotide identities among the Iranian isolates were 96-98%, and showed 94-96% identity with TYLCV-IR [IR:Ira:98] and TYLCV-IL [IL:Reo:86]. However, they showed low identity (68-69%) with ToLCIRV-[IR:Ira]. Sequence analyses of IR indicated that seven Iranian isolates had sequence identity of 93-100% with each other, and 76% identity with the Jiroft isolate; identities of 75-79% with TYLCV-IR[IR:Ira:98] were observed in every case, and 59-62% identity with ToLCIRV-[IR:Ira]. The IR nucleotide sequences of Iranian isolates showed 92-93% identity with TYLCV-IL[IL:Reo:86], except the Jiroft isolate (75%). The CP and IR sequence analyses suggested that eight Iranian TYLCV isolates probably differ from ToLCIRV-[IR:Ira]. Based on IR sequence comparisons and phylogenetic analyses, the Iranian isolates were divided into two groups. The first major group (A), consists of seven virus isolates, was most closely related to TYLCV-IL[IL:Reo:86], and relatively divergent from TYLCV-IR [IR:Ira:98] and ToLCIRV-[IR:Ira]. However, the Jiroft isolate from group B did not show high similarity with TYLCV-IR[IR:Ira:98], ToLCIRV-[IR:Ira], and TYLCV-IL[IL:Reo:86], suggesting that the isolate may be a divergent variant. The differences are in a range that suggests different strains or species from TYLCV-IR[IR:Ira:98] and ToLCIRV-[IR:Ira] are probably associated with tomato yellow leaf curl disease in Iran.