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Etiology

Relationships Between Barley Yellow Dwarf and Beet Western Yellows Viruses. W. F. Rochow, Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, also Professor of Plant Pathology, Cornell University, Ithaca, NY 14853; James E. Duffus, Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, U.S. Agricultural Research Station, P.O. Box 5098, Salinas, CA 93901. Phytopathology 68:51-58. Accepted for publication 21 June 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-51.

When concentrated preparations of the MAV or PAV isolates of barley yellow dwarf virus (BYDV) were tested against antisera of four isolates of beet western yellows virus (BWYV), no reactions occurred in any of several kinds of tests. But the RPV isolate of BYDV consistently reacted with antisera (diluted 1:5) for the E-4, ST-1, and ST-9 isolates of BWYV. Reactions were detected both in antiserum absorption tests assayed by sucrose density gradient centrifugation, and in infectivity neutralization tests assayed by the serological blocking of virus transmission by aphids fed on treated inocula through membranes. Similar results occurred when treated virus preparations were assayed by injection into aphid vectors. With about 12 μg of RPV isolate, a reaction was detected in tests with antisera for the E-4 and ST-9 isolates of BWYV diluted up to 1:125. In comparative transmission tests, Myzus persicae occasionally transmitted the four isolates of BWYV to Coast Black oats. Transmission of the ST-9 isolate, for example, occurred in 4 of 5 experiments in which ST-9 was recovered from 11 of 23 inoculated oat plants, none of which developed symptoms. None of 128 attempts to transmit BWYV to oats by means of Rhopalosiphum padi or Macrosiphum avenae was successful, but M. avenae occasionally transmitted BWYV to shepherd’s purse plants. None of 164 shepherd’s purse plants became infected with the three isolates of BYDV. The relationship of the RPV isolate of BYDV to BWYV could have a special significance in epidemiology of these luteoviruses because of RPV’s role as a helper virus in dependent virus transmission by aphids from mixed infections.