ABSTRACT

Supplemental quicktime MOVIE data for these nuclei.

Bass H.W., Nagar S., Hanley-Bowdoin L., and Robertson D. (2000) 
    Chromosome condensation induced by geminivirus infection of mature plant 
    cells. Journal Cell Science 113(7):1149-1160. 
    (cover page) (JCS online Abstract) (cover jpg)

Abstract.
     The geminivirus, tomato golden mosaic virus (TGMV), replicates 
its single-stranded DNA genome through double-stranded DNA 
intermediates in nuclei of differentiated plant cells using host replication 
machinery. We analyzed the distribution of viral and plant DNA in 
nuclei of infected leaves using fluorescence in situ hybridization (FISH). 
TGMV-infected nuclei showed up to a six-fold increase in total volume 
and displayed a variety of viral DNA accumulation patterns. The most 
striking viral DNA patterns were bright, discrete intranuclear 
compartments, but diffuse nuclear localization was also observed. 
Quantitative and spatial measurements revealed that these 
compartments accounted for 1 - 18% of the total nuclear volume or 2 - 
45% of the total nuclear FISH signals.  In contrast, plant DNA was 
concentrated around the nuclear periphery. In a significant number of 
nuclei, the peripheral chromatin was organized as condensed prophase-
like fibers. A combination of  FISH analysis and indirect 
immunofluorescence with viral coat protein antibodies revealed that 
TGMV virions are associated with the viral DNA compartments. 
However, the coat protein antibodies failed to cross react with some 
large viral DNA inclusions, suggesting that encapsidation may occur 
after significant viral DNA accumulation. Infection by a TGMV mutant 
with a defective coat protein open reading frame resulted in fewer and 
smaller viral DNA-containing compartments, possibly because single-
stranded DNA was not stabilized in virions. Nuclei infected with the 
mutant virus increased in size and in some cases showed chromosome 
condensation. Together, these results established that geminivirus 
infection alters nuclear architecture and can induce plant chromatin 
condensation characteristic of cells arrested in early mitosis. 


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