Pathogen considerations in the deployment of bioenergy grass crops

Background/Question/Methods

With interest in cellulosic ethanol rising, fast-growing perennial grasses may be planted over large areas of the Midwestern United States and elsewhere.  This possible large-scale change in vegetation cover has potential to promote biodiversity and enhance ecosystem services, particularly if native species are used. However, there remain some substantial unknowns about biodiversity responses, particularly among less studied taxa. One less-studied taxonomic group that merits significant attention are plant viruses. Recognized for some time in agricultural crops, plant viruses have received less attention in natural ecosystems. Development of perennial grass biofuel crops raises the possibility that such perennial plantings could serve as long-term reservoirs of pathogenic viruses that might be spread into food crops by generalist insect vectors.  Alternatively, diverse perennial plantings could equally well provide refuges for beneficial insects and reduce virus pressure overall. Here we summarize current understanding of the influence of plant traits, community diversity, and landscape context on virus pressure in biofuel grasses.

Results/Conclusions

Virus infection in perennial grasses is generally difficult to detect by visual inspection and thus easily can be overlooked; monitoring of plants and vectors with diagnostic assays is required. Modification of the traits of perennial grasses for biofuel production through selection for increased growth rates may increase plant susceptibility to virus infection. However, increased plant diversity at local and landscape scales may reduce vector and virus pressure. Current understanding suggests that risk of exchange of some viruses among food and fuel crops has potential to be reduced by appropriate choice of crop traits and management of biodiversity patterns.  Whether this might be true for the full suite of plant viruses found in these ecosystems requires more attention.