VIEW ARTICLE

Cytology and Histology

Assembly, Morphology, and Accumulation of a Hawaiian Isolate of Maize Mosaic Virus in Maize. L. L. McDaniel, Research associate, Department of Plant Pathology, The Ohio State University (OSU), Ohio Agricultural Research and Development Center (OARDC), Wooster 44691; E.-D. Ammar(2), and D. T. Gordon(3). (2)Visiting professor, Department of Entomology (OSU, OARDC), on a Fulbright Scholarship from the Department of Economic Entomology, Faculty of Agriculture, Cairo University, Giza, Egypt; (3)Professor, Department of Plant Pathology, The Ohio State University (OSU), Ohio Agricultural Research and Development Center (OARDC), Wooster 44691. Phytopathology 75:1167-1172. Accepted for publication 23 May 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-1167.

Large accumulations of bullet-shaped and bacilliform particles of a Hawaiian isolate of maize mosaic virus (MMV) were present in the perinuclear space and cytoplasm of epidermal, mesophyll, and vascular parenchyma cells and phloem and xylem elements of infected maize (Zea mays). Particles budded through the inner and, less frequently, the outer nuclear membranes and through cytoplasmic membranes. Particles were seen infrequently in the nucleus and only within membrane-bound vesicles that presumably originated from invaginations of the proliferated nuclear membrane. Average particle lengths for bullet-shaped and bacilliform particles in vivo were 244 and 253 nm, respectively; diameters of both, including surface projections, averaged 62 nm. Preparations of glutaraldehyde-fixed, partially purified MMV particles stained with uranyl acetate (UA) (pH 4.0), potassium phosphotungstate (PTA) (pH 7.0), or ammonium uranyl oxalate (AUO) (pH 7.0) contained more bacilliform particles than did preparations of unfixed, similarly stained particles. The virion nucleocapsid was bullet-shaped, as determined by removal of the envelope with Triton X-100. UA caused rupture and collapse of some unfixed particle envelopes, which enfolded upon the nucleocapsid giving an anomalous particle morphology, and PTA caused fragmentation of particles which gave short, stubby rods. AUO did not cause either artifact. Average length and diameter of bullet-shaped particles from partially purified preparations stained with UA were 204 x 67 nm and of the bacilliform particles were 245 x 80 nm. Particles from these preparations were infective.