Evidence of changes in chromosome morphology in root tips of Nicotiana tabacum L. cv. 'Samsun' after infection with tobacco mosaic virus
1993
Buech, K. (Tuebingen Univ. (Germany). Biologisches Inst.) | Sander, E.
When the karyotype of Nicotiana tabacum L. cv. 'Samsun' was examined in 60 root tips in each case of three plants prior to inoculation with tobacco mosaic virus and 26 and 34 d post infectionen (p.i.), the number of chromosomes (2n 48) and the ratio of six nucleoli to six satellites remained the same, but there were changes in the morphology of several chromosomes after virus infection of the plants. The satellites of the two largest satellite-bearing chromosomes had doubled in size, the long arms of chromosomes 37 and 38 had significantly shortened, and so had the short arms of chromosomes 43. Also, the total length of the chromosome set was reduced from 114.50 mim (non-inf.) to 106.50 mim (inf.), and the indices of proportion (Gi) and symmetry (Si) had changed. The changes in chromatin are interpreted in connection with telomeres and stress effects. Virus infection was assessed in the above- and below-ground plant parts primarily by immuno-assay (DAS-ELISA) and by the occurrence of typical TMV inclusion bodies. There was a gradient in virus content in the plant (26 d p.i.), being highest in the basal leaves, less in the plant apex, and least in root tips (7.88, 3.46 and 1.54 mg TMV/g tissue, respectively). A novel comparison of virus content and inclusion bodies showed that despite the difference in TMV titre, the frequency of inclusion bodies in cells of root tips and leaf hairs was comparable
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