PVX MS, a New Strain of Potato Virus that Overcomes the Extreme Resistance Gene <i>Rx</i>

Abstract

Abstract A new resistance‐breaking isolate of potato virus X (PVX MS; also called PVX fcaOl) that multiplies in genotypes carrying the Rx gene was detected in Argentina. Enzyme‐linked immunosorbent assay (ELISA) assessment of PVX multiplication in mechanically inoculated micropropagated plantlets revealed that PVX MS is able to replicate in both resistant ( Rx ) and suceptible plantlets whereas strain PVX cp is able to replicate only in the latter. Immunoblot detection with specific monoclonal an, tibodies showed that PVX MS belongs to the serotype PVX o (common or European strain), whereas PVX HB is included in the serotype PVX A (Andean). SDS polyacrylamide gel electrophoresis followed by immunoblotting of the coat proteins of the PVXst, rains cp, cp4, HB, and MS showed that they differed in mobility with apparent mol. wts of 27.9, 28.8, 29.9, and 29.4 kDa, respectively.