First Report of Soilborne Rye Mosaic Virus in Rye in Denmark

Area of Science:

• Plant Pathology
• Virology
• Cereal Science

Background:

• Soilborne plant viruses pose significant threats to cereal production worldwide.
• Furoviruses are known to infect various crops, including cereals, causing yield losses.
• Previous records of soilborne rye mosaic virus (SBRMV) were limited to Germany.

Purpose of the Study:

• To identify and characterize a virus detected in rye plants exhibiting mosaic symptoms in Denmark.
• To determine the phylogenetic relationship of the new virus isolate to known furoviruses.
• To establish the first record of a furovirus in Danish cereals.

Main Methods:

• Electron microscopy was used to visualize virus particles and determine their morphology.
• Mechanical sap inoculation was performed on indicator plants (Chenopodium quinoa and C. amaranticolor) at different temperatures.
• Immunosorbent electron microscopy (ISEM) was employed using specific polyclonal antiserum.
• Nucleotide sequencing was conducted to analyze the complete genome of the isolate.
• Light microscopy was used to examine root structures for potential vectors.

Main Results:

• Virus particles consistent with furoviruses, measuring 296 and 162 nm in length and 23 nm in diameter, were observed.
• Symptoms were induced in indicator plants at 17°C but not at higher temperatures (22-25°C).
• ISEM confirmed the furovirus nature of the particles.
• Resting spores resembling the furovirus vector *Polymyxa graminis* were found in infected roots.
• Sequence analysis revealed only 74% identity to soilborne wheat mosaic virus (SBWMV), supporting its designation as a distinct species.
• The virus was named soilborne rye mosaic virus (SBRMV).

Conclusions:

• A novel furovirus, SBRMV, has been identified in rye in Denmark.
• This finding represents the first record of a furovirus infecting cereals in Denmark.
• The genetic distinctness of SBRMV from SBWMV warrants its classification as a separate virus species.