ULTRASTRUCTURAL FEATURES OF BETA LEAVES INFECTED WITH BEET YELLOWS VIRUS

Abstract

A cytochemical and electron microscope study has been made of leaves of sugar beet infected with beet yellows virus. Inclusions of particles, which agree in size with beet yellows virus particles isolated by other investigators, have been localized in the ground cytoplasm, in the chloroplasts, and in the nuclei. These particles are circa 100 A in diameter and have an electron-transparent core of 30 to 40 A. Use of acridine orange, azure B, and pyronine Y has revealed that the cytoplasmic inclusion bodies, which consist wholly of the elongate particles, have a strong RNA reaction removable by RNase pretreatment. Particles observed in the chloroplasts may or may not be associated with lipid spheres. If they are, the particles are confined to the periphery of the spheres. In this position the particles are arranged tangentially and are further arranged parallel into groups which lie at various angles to one another. Within the groups the particles are regularly spaced in a three dimensional lattice. Particles located free in the stromal regions are often arranged regularly in curved rows which lie parallel to one another so that a three dimensional lattice is formed. The dispersed and compact forms of virus inclusions are described and related to the condition of the associated cytoplasm. The ground cytoplasm of cells associated with the sieve elements contains numerous ribosomes. A decrease in the number of ribosomes is concomitant with the increase in size of virus aggregations in a cell. Vesiculation of some component of the cytoplasm occurs during the period of virus replication. The vesicles are approximately 100 m/z in diameter and could be derived from the dictyosomes. At late1 stages of infection these vesicles collapse and convoluted membranous material appears.

ULTRASTRUCTURAL CHANGES IN CHLOROPLASTS OF PHASEOLUS VULGARIS DURING DEVELOPMENT UNDER CONDITIONS OF NUTRIENT DEFICIENCY

“…The Type C pattern appeared similar to that of phytoferritin as described by Hyde et al (1963), by Cronshaw et al (1966), and by Robards and Humpherson {i()(i'j). The last-named indicated that phytoferritin is normally present only in cells at an early stage of differentiation or in plastids incapable of full photosynthetic activity.…”

Ultrastructural changes in rust-infected tissues of flax and sunflower

“…At periods of 5,6,8,9,11,12,13, and 15 days after inoculation, the diseased tissue was dissected into 1-rnm squares and placed in 3% glutaraldehyde in 0.05 M potassium phosphate buffer at pH 6.8 for 19 h. Dissection of tissue was carried out 2 h after the start of each daily light period. After fixation, the tissue was rinsed in several changes of the buffer for 1 h and postfixed in 2% Os04 in 0.05 M phosphate buffer at pH 6.8 for 2 h. After dehydration in an acetone series and propylene oxide, the material was embedded in a plastic mixture consisting of Epon, Araldite, and dodecenyl succinic anhydride in the ratio 3:3:8 by volume, using dimethyl phthalate 30 as an accelerator.…”

Ferreting out the secrets of plant ferritin ‐ A review

“…1961;Rossner, 1960;Schnepf, 1961), viral inclusions (Cronshaw et al, 1966) or just electron dense inclusions (Sprey et al, 1976)?…”

“…Such patterns, lamellae-disks alternating within the plastidal inclusion organized in F-4 array have been observed by several investigators. Cronshaw et al (1966) and Kim and Fulton (1969) have alternatively interpreted such crystalline pattern as viral rod particles or filaments, respectively. Scattered particles (S) and square (SQ) arrays are also visible in this micrograph.…”

“…They ignored the botanical ferritin in spite of its existence as depicted particles in their micrographs (see Behnke, 1978, p. 349). Other plant ultracytologists, however misinterpreted the ferritin particles and considered them as viral aggregates (Cronshaw et al, 1966). In later publications, such inaccuracy has been partially corrected (Esau, 1968;Robards and Robinson, 1968).…”