Immunological and molecular studies on barley yellow dwarf virus
Abstract
Immunological and molecular properties relating to the diagnosis and control of barley yellow dwarf virus (BYDV) were investigated. Three murine monoclonal antibodies MAbs), AF8, AG12 and BA6, were produced using BYDV isolate MAV-PS1 as the antigen source. All these reacted similarly with MAV-PS1, and also detected other MAV, PAV and SGV serotype isolates, but failed to detect RPV and RMV serotype isolates. Dissociation of virus particles in sodium carbonate and varying enzyme-linked immunosorbent assay (ELISA) procedures substantially changed their serological reactivity. By transfers via single aphids, serological variants were isolated from the type MAV isolate (NY-MAV). In reacting with two MAbs these subcultures behaved similarly to a subculture of NY-MAV previously established at Purdue (MAV-PS1) which, in contrast to NY-MAV, reacts with an MAb, MAV1, but not with another MAb, MAV3. By two-site ELISA, variants containing both MAV1- and MAV3-reacting epitopes were detected, indicating that the NY-MAV is a mixture including at least two serological variants. Most samples collected in Central and South America were like MAV-PS1, in reacting with these two MAbs. Symptomatically, MAV-PS1 and NY-MAV were similarly severe, although reddening was slightly more obvious on plants infected with NY-MAV. In establishing potato as a model for cereal transformation with the BYDV coat protein (CP) gene, fifty leaf strips and 25 tuber discs regenerated 115 and 10 independent potato plants, at 98% and 28% transformation efficiency, respectively. The CP gene was expressed at least to the RNA level. Although it was not clear if the expression conferred resistance to a BYDV-related virus--potato leafroll virus, this work provides useful background information regarding the problem of conferring CP-mediated BYDV resistance to cereals. The nucleotide sequences of the CP gene and viral genome associated protein (VPg) regions of the genomes of BYDV isolates NY-SGV and TX-SGV were determined. Comparison of these with similar genomic regions of other BYDV isolates indicated that SGV is a distinct serotype and resembles the MAV and PAV serotypes more than the RPV serotype. Despite differing in vector relationships, NY-SGV and TX-SGV were closely similar in the CP and VPg genomic regions.
Degree
Ph.D.
Advisors
Lister, Purdue University.
Subject Area
Plant pathology|Molecular biology|Microbiology
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