REPLICATION OF ALFALFA MOSAIC-VIRUS RNA-3 WITH MOVEMENT AND COAT PROTEIN GENES REPLACED BY CORRESPONDING GENES OF PRUNUS NECROTIC RINGSPOT ILARVIRUS

Alfalfa mosaic virus (AMV) and Prunus necrotic ringspot virus (PNRSV) are tripartite positive-strand RNA plant viruses that encode functiona lly similar translation products, Although the two viruses are phyloge netically closely related, they infect a very different range of natur al hosts, The coat protein (CP) gene, the movement protein (MP) gene o r both genes in AMV RNA 3 were replaced by the corresponding genes of PNRSV, The chimeric viruses were tested for heterologous encapsidation , replication in protoplasts from plants transformed with AMV replicas e genes P1 and P2 (P12 plants) and for cell-to-cell transport in P12 p lants, The chimeric viruses exhibited basic competence for encapsidati on and replication in P12 protoplasts and for a low level of cell-to-c ell movement in P12 plants, The potential involvement of the MP gene i n determining host specificity in ilarviruses is discussed.