A Note on the Effects of a Product of Aspergillus niger on Nuclei of Allium cepa

Abstract

A heat stabile substance was produced by A. niger, accumulated in the culture medium, and induced nuclear area and nuclear dry mass decreases in inner epidermal cells of onion bulb scales comparable to decreases observed 0-5mm ahead of mycelium in infected bulbs. When tissue squares 5mm on a side were incubated in culture filtrate, half of the cells were dead after 15 seconds incubation and all were dead in 15 minutes. Because the effects of infective mycelium and culture filtrate were comparable in kind of nuclear changes produced and similar in magnitude of these changes, we suggest that the same substance was produced by the fungus in vitro as during infection.