Molecular and biological detection of impatiens necrotic spot virus (INSV) isolate from ornamental plants in Iran

Abstract

Impatiens necrotic spot virus (INSV), belong to genus Orthotospovirus, causes severe damage to greenhouse ornamental plants. INSV reported from almost every ornamental screen house in Iran. INSV general symptoms include necrotic leaf spot, chlorosis and stunting in infected ornamental host plants. A total number of 581 ornamental samples of 58 different plant species with symptoms similar to those of INSV infection were collected in 4 provinces of Iran. The results indicated an average of 20.13 per cent virus incidence. INSV infection was recorded to be 28% in Mahallat, 24.5% in Tehran, 22.1% in Mazandaran and 16.4% in Guilan provinces. No record of INSV infection on ornamental samples was obtained from Khouzistan province (Dezful). From the total of 58 ornamental species tested, 33 species recorded positive for INSV. ELISA positive samples were rechecked by RT-PCR using a set of specific primers directed to the N-gene region, which were designed to detect and characterize the virus species. The primers ampl fied a 777 bp product of the nucleoprotein as shown by agarose gel electrophoresis. The nucleotide sequence of amplicons was compared with related sequences, using Blast software available at NCBI GenBank, which showed highest similarity with impatiens necrotic spot virus (INSV) isolates. Accordingly, all genome components of the isolate shared 89-96.5 % nucleotide sequence identities with corresponding sequence of other Iranian and GenBank INSV isolates. The Iranian isolates were all placed in the same group and bore the most similarity to INSV isolates from the Netherlands, Italy and United States. In phylogenetic analysis based on the partial nucleotide and deduced amino acid sequences of N region, INSV from Iran appears to be closely related to the Japanese AB1099100 Verbena spp. isolate.