Nuclear changes in allium cepa in response to infection by fusarium moniliforme

Abstract

Fusarium moniliforme was isolated [into culture] from white onion and inoculated into holes bored in onion bulbs. After 48 hrs, the nuclear dry mass of onion cells 0–5 mm ahead of the mycelium had decreased by 19% as determined by quantitative interference microscopy as compared to nuclear dry mass decreases of 11 % caused by avirulent Aspergillus niger, 26 % by an unidentified onion pathogen, 41 % by virulent Botrytis allii, and 42 % by virulent Aspergillus niger. In the present study, the nucleolar dry mass declined by 34 % in response to F. moniliforme under the same conditions. Degradation or exit of nuclear and nucleolar macromolecules in response to fungal products secreted in advance of mycelium may be responsible for lower nuclear and nucleolar dry mass.