Is Fusaric Acid a Vivotoxin?

Abstract

WHILE fusaric acid has been isolated and identified from culture filtrates of a number of Fusaria, its detection in vivo in diseased host plants has not yet been achieved in order to establish its vivotoxic complicity in wilt diseases¹. Recent work of Zähner² on the detection and estimation of fusaric acid by chromatographic and bioassay techniques suggests the possibility of detection of fusaric acid in vivo in wilting host plants. We have been employing various chromatographic techniques, particularly the circular macro-³ and micro-⁴ techniques developed by one of us, for the detection and quantitative estimation of fusaric acid, and experienced considerable difficulty in obtaining sharp demarcation of the bands and reproducible R _F values to facilitate quantitative estimation. Fusaric acid detected with brom cresol green indicator gives a diffused and ill-defined yellow band in a blue background, possibly due to the poor ionization of the acid. The difficulty was overcome by preliminary conversion of fusaric acid into its copper complex on the filter paper with copper sulphate and irrigating the complex with excess copper with n-butanol/acetic acid/water (4: 1: 5). The quantitative estimation of fusaric acid has been carried out with this technique based on the area method and will be published shortly; we have used the technique for the detection of fusaric acid in vivo in wilted cotton plants.