|Author: ||E. Seemüller|
Bark samples of apple and pear trees showing proliferation or pear decline symptoms were sectioned with the freezing microtom.
The sections were treated with 4'-6-diamidino-2-phenylindole (DAPI). In almost all of the samples examined characteristic fluorescent particles could be observed in the sieve tubes.
This fluorescence which seems to be related to the occurence of mycoplasma like organisms was absent in samples from healthy looking trees.
For comparison stem pieces of periwinckle plants (Catharanthus roseus) graft inoculated with aster yellows were investigated as well as healthy ones.
In the infected plants the same fluorescence symptoms as in the diseased apple and pear trees could be detected.
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