|Authors: ||S. S. Hearon, Roger H. Lawson|
By examining carnation etched ring virus infected Saponaria vaccaria leaves from plants grown at 22, 27, or 32 C, we found that temperature induced variations in symptom expression are accompanied by variations in the cell and virus inclusion ultrastructural appearance, in virion accumulation and in levels of infectivity.
Optimal temperature for rapid symptom expression, inclusion maturation and rapid increase in infectivity is 27 C. At 22 C the appearance of symptoms, the rise in infectivity, and the maturation of cytoplasmic inclusions is slow.
Accumulation of virions in the nuclei is delayed to a greater extend than in the cytoplasmic inclusion.
At 32 C, virions quickly appear in the nuclei and commonly are found in the nuclear pores, but abnormal inclusions with limited numbers of virions and quantities of matrix protein are formed in the cytoplasm.
The ultrastructural appearance of the nucleoli and the plasmadesmata are also modified by temperature conditions.
As the temperature is increased the size of the F regions in the nucleoli decreases and that of the G regions increases.
At 32 C, F regions are small and the G regions contain granular particles but the amount of surrounding matrix is reduced.
As the temperature is increased the extent of the modification in the plasmadesmata decreases.
At 21 C virion-containing plasmadesmata are greatly extended, but at 32 C even slightly extended plasmadesmata are seldom seen.
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