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Evidence for Infectivity of Maize Chlorotic Dwarf Virus and for a Helper Component in Its Leafhopper Transmission. R. E. Hunt, Graduate research associate, Department of Entomology, The Ohio State University (OSU), Ohio Agricultural Research and Development Center (OARDC); L. R. Nault(2), and R. E. Gingery(3). (2)Professor, Department of Entomology, The Ohio State University (OSU), Ohio Agricultural Research and Development Center (OARDC); (3)Research chemist, U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS), Department of Plant Pathology, OSU-OARDC, Wooster 44691. Phytopathology 78:499-504. Accepted for publication 30 October 1987. 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, 1988. DOI: 10.1094/Phyto-78-499.

The infectivity of maize chlorotic dwarf virus (MCDV) was demonstrated indirectly by in vivo neutralization of infectivity in its leafhopper vector, Graminella nigrifrons, and directly by leafhopper transmission of purified virus acquired through parafilm membranes. In neutralization of infectivity tests, transmission of MCDV by viruliferous leafhoppers was reduced (more than eightfold) if they were allowed to feed through parafilm membranes on a suspension containing MCDV antiserum or its IgG fraction compared to control leafhoppers fed on preimmune serum. Leafhoppers given access to membranes containing suspensions of crude, clarified, or concentrated extracts of MCDV or purified virus did not transmit virus to healthy maize plants. However, transmission of a purified isolate (MCDV-white stripe) acquired by membrane feeding occurred if leafhoppers had previously fed on plants infected with another isolate (MCDV-mild), but not if they had first fed on healthy plants or plants infected with maize dwarf mosaic virus. Reversing the feeding sequence, when leafhoppers first fed on membranes containing MCDV-white stripe and then on plants infected with MCDV-mild, they did not transmit MCDV-white stripe. These experiments strongly suggest that a helper component produced in MCDV-infected plants is necessary for the transmission of MCDV by its leafhopper vectors. Use of the term “transitory” by some authors to describe the semipersistent transmission of MCDV and the related rice tungro viruses is discussed.

Additional keywords: virus-vector relationships.