BARLEY YELLOW DWARF VIRUS ISOLATE-SPECIFIC RESISTANCE IN SPRING OATS REDUCED VIRUS ACCUMULATION AND APHID TRANSMISSION

Resistance to barley yellow dwarf virus in a spring oat genotype was m anifested as a reduction in accumulation of viral antigen in whole pla nts. The resistance was quantified for five isolates of BYDV from New York (MAV, PAV, SGV, RPV, and RMV) and found to be BYDV isolate specif ic. Similar levels of resistance were quantified for MAV, PAV, and SGV in which the reduction in viral antigen ranged from 58-63 percent, re lative to levels in a susceptible genotype. RMV antigen was reduced up to 82 percent, but no resistance was expressed against the RPV isolat e. Reduced viral antigen was correlated with reduced levels of transmi ssion of MAV, PAV, SGV, and RMV, but not RPV. Further reductions in tr ansmission efficiency were possible by limiting the acquisition access period. Resistance to circulative, nonpropagative, aphid-borne viruse s manifested as a reduction in virus antigen may reduce the spread of disease among plants, especially if coupled with aphid resistance mani fested as a feeding deterrent.