Relationships Between Barley Yellow Dwarf and Beet Western Yellows Viruses

Abstract

When concentrated preparations of the MAV or PAV isolates of barley yellow dwarf virus (BYDV) were tested against antisera of 4 isolates of beet western yellows virus (BWYV), no reactions occurred in any of several kinds of tests. 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 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 .mu.g 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 4 isolated of BWYV to ''Coast Black'' oats. Transmission of the ST-9 isolate, eg. 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 3 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.