Seasonal Changes in the Chloroplast Ultrastructure in Abutilon Mosaic Virus (AbMV) infected Abutilon spec. (Malvaceae)

Abstract

Various kinds of pathological effects of the Abutilon Mosaic Virus (AbMV) in seasonal dependency have been observed on the macroscopic as well as on the microscopic level. The annual rhythmic fluctuation of light caused by the varying length and intensity of light incidence is directly correlated with the realization of symptoms, leading to an intensification of the leaf mosaic and to an increase in the light leaf areas during the summer. These macroscopic observations are correlated with an annual change in the plastid fine structure in the mesophyll of the lightest areas of the leaf. The grana‐stroma‐organization of the plastids is completely eliminated through a reduction and disorganization in the thylakoid system during the spring and summer, restored in the autumn, and preserved over the winter. This change in the plastid fine structure is limited to the leaf mesophyll. The plastids of the leaf stem, like the plastids of non‐infected plants, do not display any change in their fine structure.

Single-stranded DNA from abutilon mosaic virus is present in the plastids of infected Abutilon sellovianum

“…2) revealed that these fractions were free of mitochondria, and there were no virus-related structures that copurified with plastids. The ultrastructure of plastids from infected plants present in band C was similar to that of degenerated plastids, which are generally found in the yellow mosaic regions of the mesophyll (11,17) (Fig. 2B).…”

“…Ultrathin sections of leaf tissue had shown that plastids lose their lamellar structure and part of their stability (11,17). This could explain why DNA from other geminiviruses was not found in these organelles, unless the AbMV is an exception.…”

“…The appearance of virus-associated structures in plastids could explain why cytological symptoms of the disease are predominant in the mesophyll chloroplasts, whereas they are generally absent from the plastids of the vascular-bundle area (11). Therefore, the question arises whether AbMV DNA is present in the plastids.…”

Light-dependent segregation of begomoviruses in Asystasia gangetica leaves

“…In previous studies, with Abutilon mosaic virus (AbMV) and Sida micrantha mosaic viruses (SimMVs), light intensity as well as the daily amount of light influenced the macroscopic symptoms, as well as the ultra-structure of plastids (Jeske, 1986;Werz, 1978, 1980;Schuchalter-Eicke and Jeske, 1983). It was therefore of interest to investigate the light dependence for virus infection in A. gangetica plants.…”

Indian Cassava Mosaic Virus: Ultrastructure of Infected Cells

“…It is unclear whether they contain virus particle protein. By comparison with these effects on nuclei, few whitefly-transmitted geminiviruses are known to have large effects on cytoplasmic constituents other than chloroplasts, which, however, may be greatly affected (Jeske & Werz, 1978;Schuchalter-Eicke & Jeske, 1983).…”