No abstract

During a survey, 148 wheat, 70 barley and 24 wild grass samples of plants showing symptoms of yellowing or reddening of leaves and general stunting were collected in central and southern provinces of Iran and tested for Barley yellow dwarf virus (BYDV) and Cereal yellow dwarf virus (CYDV) infection by enzymelinked immunosorbent assay (ELISA) and tissue print immunoassay (TPIA). The results showed the presence of the viruses in most regions. Positive reactions to BYDV-PAV, BYDV-MAV, CYDV-RPV and BYDV-SGV antisera were recorded. BYDV-PAV was the most prevalent virus. The genetic diversity of BYDV-PAV isolates in central and southern provinces was studied by analysing ORF1 (903 nt) and read through domain (RTD) (575 nt) of 13 and nine isolates respectively. Sequence analysis of RTD at nucleotide and amino acid levels revealed a high identity (91.8-97.2% and 91.4-100% respectively) between Iranian and other available isolates in the GenBank. However, in regards to ORF1, a high genetic diversity among Iranian and other known PAV isolates at both amino acid (2-16.9%) and nucleotide (4.1-16.5%) levels were detected. Based on phylogenetic analysis of ORF1, two major groups of BYDV-PAV isolates were distinguished. The Iranian isolates were divided between the two clusters. Our results suggest that the occurrence of two genetically distinct groups of PAV isolates in central and southern Iran, from which according to the ICTV criteria for species demarcation in the family Luteoviridae, four isolates from central parts of the country, qualify for designation as new species.