The first complete genome sequence of iris severe mosaic virus

Area of Science:

• Plant Virology
• Genomics
• Molecular Biology

Background:

• Iris severe mosaic virus (ISMV) is a plant pathogen with an unknown genomic structure.
• Understanding the ISMV genome is crucial for developing effective disease management strategies in iris cultivation.

Purpose of the Study:

• To determine the complete genome sequence of ISMV.
• To analyze the genetic characteristics and evolutionary relationships of ISMV.
• To confirm the taxonomic classification of ISMV within the Potyvirus genus.

Main Methods:

• Deep sequencing of a small RNA library from ISMV-infected samples.
• Rapid amplification of cDNA ends (RACE) PCR for genome end determination.
• Bioinformatic analyses including BLAST for identifying open reading frames and cleavage sites, and phylogenetic analysis of polyprotein sequences.

Main Results:

• The complete genome sequence of ISMV was determined, comprising 10,403 nucleotides (excluding the poly(A) tail).
• A large open reading frame encodes a 3316-amino acid polyprotein with identified putative proteolytic cleavage sites.
• Highest amino acid sequence identity was observed with the onion yellow dwarf virus polyprotein.
• Phylogenetic analysis placed ISMV within a distinct cluster of Potyvirus species, including shallot yellow stripe virus and onion yellow dwarf virus.

Conclusions:

• The complete genome sequence provides fundamental insights into the genetic makeup of ISMV.
• ISMV shares evolutionary links with other viruses in the Potyvirus genus, particularly those affecting Allium species.
• These findings confirm ISMV as a distinct species within the genus Potyvirus, aiding in its accurate classification and further research.