First Report of a Furovirus Infecting Field-Grown Rye in North America.

Abstract

Viral symptoms were present in a dwarf recurrent population (99RP17) of rye (Secale cereale) at the North Florida Research and Education Center in Quincy, Gadsden County, FL, during the winter and spring of 2000. Symptoms and distribution of the infected plants in the field were similar to those caused by Soilborne wheat mosaic virus (SBWMV; acronym WSBMV), which was first recognized in North America in 1919 (4) and found in Florida in wheat in 1970 (3). SBWMV has been observed based on symptoms in rye in North America (4). Interveinal, non-continuous, chlorotic areas of leaves and stunting of plants in patchy patterns occurred in four locations (0.8 to 1.6 km between locations). Incidences of the disease ranged from 3 to 15%. Leaves and roots of more than 25 plants were assessed. Using light microscopy, after staining with Calcomine Orange 2RS/Luxol Brilliant Green BL (1), amorphous, vacuolate inclusions were observed in all assayed leaves. With electron microscopy, rigid rods were present with a bimodal distribution of particle lengths that conformed to size distributions found originally in wheat in 1970 in Florida. Leaves with symptoms were sent to Agdia Inc. (Elkhart, IN) and samples were strongly positive for SBWMV using enzyme-linked immunosorbent assay. Cystosori of Polymyxa graminis were detected from a few roots from symptomatic plants. While these associations are suggestive of SBWMV, and rye is a reported host of SBWMV, the possibility of this virus being soilborne rye mosaic virus exists (2). Such a differentiation will require nucleotide sequence analysis. To our knowledge, this is the first report of a furovirus infecting field-grown rye in Florida and in North America.