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Etiology

Purification and Properties of an Isolate of Maize Rayado Fino Virus from the United States. R. E. Gingery, Research chemist, Agricultural Research Service, Science and Education, U. S. Department of Agriculture (ARS-S&E-USDA), Wooster 44691; D. T. Gordon(2), and L. R. Nault(3). (2)Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center (OARDC), Wooster 44691; (3)Professor, Department of Entomology, Ohio Agricultural Research and Development Center (OARDC), Wooster 44691. Phytopathology 72:1313-1318. Accepted for publication 26 February 1982. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982.. DOI: 10.1094/Phyto-72-1313.

An isolate of maize rayado fino virus from infected corn in the United States (MRFV-US) was purified by chloroform clarification, rate-zonal centrifugation, and isopycnic banding in CsCl. Yields were usually 30–80 μg of virus per gram of tissue. A noninfectious top component (47S) containing no nucleic acid, and an infectious bottom component (124S) containing a single RNA species (2.4 × 10⁶ daltons) were separated by rate-zonal centrifugation. The RNA was single-stranded, comprised 26% of the bottom component by weight, and contained 31.4% Cp, 23.1% Gp, 16.8% Ap, and 28.7% Up. The top and bottom components banded isopycnically in CsCl at densities of 1.265 and 1.425 g/ml, respectively. Two proteins (MWs 25,600 and 22,350) were found in each component in the same ratio, about three molecules of the lighter protein per molecule of the heavier. Partially purified MRFV-US had a thermal inactivation point between 90 and 100 C, dilution end point between 10^–4 and 10^–5, and longevity in vitro between 9 and 11 wk. Infectivity of partially purified preparations was preserved by lyophilization. The cryptogram for the bottom component is R/1:2.4/26:S/S:S/Au. Enzyme-linked immunosorbent assay was used to detect MRFV in individual Dalbulus maidis leafhopper vectors and to show that the amount of virus in leafhoppers declined between 0 and 7 days, increased between 7 and 14 days, and remained high through 21 days after acquisition, indicating that MRFV multiplied in this vector. Properties of MRFV-US were similar to those of the Central and South American isolates.