Phytotoxicity of fumonisins and TA-toxin to corn and tomato

06 Sep 2017

The phytotoxic effects of 5 fumonisin mycotoxins produced by Fusarium moniliforme [Gibberella fujikuroi], i.e., fumonisin A1 (FA1), A2 (FA2), B1 (FB1), B2 (FB2) and B3 (FB3), together with the aminopolyol hydrolysis products of FB1 and FB2 (AP1 and AP2, respectively) and tricarballylic acid (TCA) were compared with the host-specific phytotoxin TA-toxin (TA) produced by Alternaria alternata f.sp. lycopersici. A leaf assay was performed on detached leaves of the tomato genotypes Asc/Asc (tolerant of TA) and asc/asc (sensitive to TA) at 4 concn (0.1, 1, 10 and 100 ?smallcap?M) of each toxin. Seedlings of maize cultivars A1849W and PNR 473 and the 2 tomato genotypes were also used to assay TA, FB1, FB2 and FB3. The fumonisins caused leaf necrosis identical to that caused by TA and FB1, FB2, FB3, and TA caused significantly (P=0.01) more necrosis than the other metabolites tested. Sterile distilled water (control) and TCA caused no necrosis. Significantly (P=0.01) more necrosis was observed on the asc/asc genotype compared with the Asc/Asc genotype. There was no significant (P>0.05) difference between necrosis caused by autoclaved metabolites and that caused by nonautoclaved metabolites. The fumonisins caused dose-dependent reductions in shoot and root length and dry mass of maize and tomato seedlings identical to those caused by TA. The results indicated that TA and FB1 are more toxic to seedlings than are FB2 and FB3. The effects of all 4 toxins were more pronounced on seedlings of the sensitive tomato genotype asc/asc than on the tolerant genotype Asc/Asc. No significant differences were recorded in the reaction of the 2 maize cultivars. The structural similarity of the fumonisin B mycotoxins and TA is therefore reflected by their phytotoxicity to detached tomato leaves as well as to maize and tomato seedlings.