Complete nucleotide sequence of Iranian tomato yellow leaf curl virus isolate: further evidence for natural recombination amongst begomoviruses

Summary. Complete nucleotide sequence of the Iranian strain of tomato yellow leaf curl virus (TYLCV-IR) was determined and compared with some begomoviruses. The complete sequence of TYLCV-IR clustered together with TYLCV and TYLCV-MId from Israel. A similar relationship holds when the deduced amino acid sequences of V1, V2, C2 and C3 and nucleotide sequences of IR, and RIR were compared. In contrast, phylogenetic analyses of amino acid sequences of C4, C1, and nucleotide sequences of LIR revealed that TYLCV-IR clustered with TLCIRV and two Indian species: ToLCBV- [Ban4], and ToLCKV. The phylogenetic analyses, Recombination Detection Program analyses, and sequence alignment survey provided evidence of the occurrence of recombination between an Israeli TYLCV-MId, as major parent, and TLCIRV, as minor parent. In this recombination event, a region (from nt 2149 to 2766) of TYLCV-MId genome were replaced with corresponding genome sequences of TLCIRV (RDP P-value = 5.976 × 10^–72), which include LIR, C4, and N-terminal of C1. Infectivity of the cloned TYLCV-IR genome was demonstrated by successful agroinoculation of tomato (Lycopersicon esculentum) and other plant species. The disease was transmitted by the natural vector Bemisia tabaci from agroinoculated plants to test plants, reproducing in this way the full biological cycle and proving that the genome of TYLCV-IR consists of only one circular single-stranded DNA molecule.