واکاوی تکاملی ژن V1 در جدایه‌های ایرانی ویروس پیچیدگی برگ‌زرد گوجه‌فرنگی

Tomato yellow leaf curl virus (TYLCV) belongs to the family Geminiviridae and genus Begomovirus. The members of this family include isometric viruses, whose particles are twinned with a circular single-stranded DNA genome of 2.787 kb. The virus genome encodes six open reading frames, two of which are located on the virion strand (V1 and V2) and four on the complementary strand (C1, C2, C3, and C4). The V1 product is a coat protein whose function is to protect the virus genome and vector transmission. This study was conducted with the aim of determining the evolutionary characteristics of V1 among Iranian isolates of TYLCV. Total number of 23 V1 nucleotide sequences from different TYLCV isolates were extracted from the GenBank and analyzed. Nucleotide polymorphism was analyzed using DnaSP software version 6.12.03 among the sequences and insertion-deletion (InDel) polymorphism was analyzed among the sequences. Non-synonymous (dN) and synonymous (dS) substitution values and the dN/dS coefficient were determined to determine the natural selection pressure on nucleotide sequences and V1 codons. Total number of 14 haplotypes were found among the sequences and 47 polymorphic loci with haplotype and nucleotide diversity of 0.945 and 0.01875 were determined, respectively. The average number of nucleotide differences was 11.360. InDel polymorphism was not found among the sequences and dN and dS values were determined as -0.5978 and -0.7394, respectively, both of which were not significant. Also, dN/dS coefficient was 0.8084. At least, six recombination events were found in different nucleotide positions. The results indicate the diversity of the V1 nucleotide sequence in different TYLCV isolates, which can be effective in the protective role and transmission activity of the virus in different hosts. Also, the variation in this part of the virus genome can affect its host range and transmissibility.