Cytokinin-like Activity of 8-Quinolinol Sulphate

Abstract

CHUA¹ has recently reported that 8-quinolinol sulphate, a compound with known antifungal and antibacterial properties, also has cytokinin-like activity. This conclusion was based on the fact that 8-quinolinol sulphate retarded the senescence of excised oat leaves. Two facts tend to diminish the validity of this conclusion: the bioassay is not specific for cytokinins—compounds other than cytokinins defer loss of chlorophyll and protein—and bacterial contamination hastens the senescence process. Thus in non-sterile conditions (which seem to be the conditions of Chua's¹ experiment), a substance which merely inhibits micro-organism growth could indirectly retard senescence but still not in fact have cytokinin-like activity.