MAIZE WHITE LINE MOSAIC-VIRUS DOUBLE-STRANDED-RNA, REPLICATIVE STRUCTURE, AND INVITRO TRANSLATION PRODUCT ANALYSIS

The possible involvement of subgenomic RNAs in maize white line mosaic virus (MWLMV) replication was investigated. In addition to full-length genomic double-stranded (ds) RNA, dsRNA with a "subgenomic" size (2.0 kb) was detected in extracts from MWLMV-infected corn plants. The viral RNA structures synthesized in vitro by a partially purified enzyme complex from MWLMV-infected corn leaves were similar to MWLMV replicative form (RF) and replicative intermediate form in electrophoretic behavior and ribonuclease sensitivity. Two major RFs (4.2 and 2.0 kb) and two minor RFs (1.2 and 0.8 kb) were found. The two major RFs corresponded to the two major dsRNAs found in MWLMV-infected corn plant extract. In vitro translation studies showed that MWLMV RNA directed the synthesis of four major polypeptides (26, 34, 35, and 50 kDa). The 34- and 35-kDa polypeptides reacted weakly with antiserum specific to the MWLMV virion. This result and those from western-blot analysis showed that the 35-kDa translation product was the MWLMV capsid protein. A model for MWLMV genome organization is proposed based on the comparison of features of MWLMV and the well characterized viruses carnation mottle, turnip crinkle, cucumber necrosis, and maize chlorotic mottle.