Switchgrass, a biomass crop being evaluated for commercial cellulosic ethanol production, may have a virus to contend with, report University of Illinois (U of I) researchers.

The virus, belonging to the genus Marafivirus, is associated with mosaic and yellow streak symptoms on switchgrass leaves. It has the potential of reducing photosynthesis and decreasing biomass yield. Members of this genus have been known to cause severe yield losses in other crops.

“Viral diseases are potentially significant threats to bioenergy crops such as Miscanthus x giganteus, energycane and switchgrass,” says Bright Agindotan, research associate working with the Energy Biosciences Institute (EBI) in the Institute for Genomic Biology at the U of I. “Our team at EBI has been charged with identifying potential pests and pathogens of these bioenergy crops.”

Until recently, little has been known about viruses in bioenergy crops. Agindotan says most plants can be infected with multiple viruses, making it a challenge to know which viruses to start screening for, especially when only a few viruses have been reported to affect these crops.

He developed a method that allows for the identification of a virus without prior knowledge of it, successfully using sequence-independent amplification (SIA) to identify RNA viruses. This is the first time it has been fully described and used for plant virus identification.

The identified virus in switchgrass is different but related to Maize rayado fino virus (MRFV), a type member of the genus, which has been reported to cause yield reductions in corn grown in Mexico, Central America and South America. The MRFV has never been reported in Illinois.

The Marafivirus was identified in a U of I research field near campus, where 20-30% of the switchgrass plot was infected with it.

“We are still working on identifying the insects that are responsible for transmitting it,” he says. “We know that its MRFV relative is transmitted by leafhoppers in corn, but we are still trying to confirm the exact species that transmit this virus in switchgrass.”

At this time, researchers cannot confirm if this virus affects other crops.

“We don’t yet know if the marafivirus in switchgrass evolved from the one that infects maize or vice versa,” he says.

Developing biomass crops that do not harbor pathogens that can spread to nearby cultivated food crops such as cereals is a high priority for plant breeders. This discovery will help plant breeders develop resistant varieties, Agindotan says.

The group will report the full genome sequence of the switchgrass virus soon.

This study, “Application of sequence-independent amplification (SIA) for the identification of RNA viruses in bioenergy crops,” was published in the Journal of Virological Methods. Researchers include Bright Agindotan, Monday Ahonsi, Leslie Domier, Michael Gray and Carl Bradley, all with the U of I.