GENOMIC REARRANGEMENT IN GENOME SEGMENT-12 OF RICE DWARF PHYTOREOVIRUS

The genome segment 12(S12) of rice dwarf phytoreovirus (RDV) isolated from the Philippines (RDV-P) and of a variant (RDV-s-6) of RDV severe strain (RDV-S) migrated abnormally slower during polyacrylamide gel el ectrophoresis than that of the isolate maintained at Hokkaido Universi ty (RDV-H). Nucleotide sequence analysis revealed that rearrangement h ad occurred in these segments, affecting the open reading frame. A pol ypeptide encoded by S12 (Pns12) of RDV-P had a duplication of 28 amino acids while 1/3 of the carboxyl terminus of Pns12 was deleted in RDV- S-6 by premature termination due to a frameshift. RDV-S is always pres ent in plants infected with the RDV-s-6 variant, suggesting that Pns12 of RDV S-6 is defective. On the other hand, Pns12 of RDV-P was expres sed and appeared to be functional in infected cells in spite of the du plication, as demonstrated by immunoblot analyses using antibody raise d against Pns12 expressed in Escherichia coil. (C) 1996 Academic Press , Inc.