Physicochemical Characterization of Maize Mosaic Virus

Abstract

Virions of maize mosaic virus (MMV) were purified from greenhouse-grown inoculated maize plants and the physicochemical properties of the virions were determined. The best purification procedure was a modified method of those used for sonchus yellow net virus and potato yellow dwarf virus. EM of purified preparations showed virions with dimensions of 224 .+-. 21 .times. 68 .+-. 9 nm. Purified preparations injected into Peregrinus maidis, the planthopper vector of MMV, were infectious to maize test plants. MMV had a sedimentation coefficient of 774 as estimated by linear-log sucrose density gradient centrifugation. Analysis of virion proteins by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed 3 major virion proteins of relative mass (Mr): 75,000 .+-. 2000 (75K), Mr 54,000 .+-. 3200 (54K) and Mr 30,000 .+-. 1000 (30K). The 75K protein stained for carbohydrate and both the 75K and 30K proteins were solubilized by treatment of virions with nonidet P-40 (NP-40) suggesting that these are G and M proteins, respectively. The 54K protein was not solubilized by NP-40 and is interpreted as an N protein. MMW also has a single-stranded RNA of .apprx. Mr 4.2 .times. 106. MMV should be placed in the lettuce necrotic yellow virus subgroup of plant rhabdoviruses.