Submitted to: Toxicologist
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2003
Publication Date: 3/1/2003
Citation: Williams, L.D., Glenn, A.E., Bacon, C.W., Showker, A.J., Riley, R.T. 2003. INHIBITION OF CERAMIDE SYNTHASE IN CORN SEEDLINGS INFECTED WITH FUSARIUM VERTICILLIOIDES OR EXPOSED DIRECTLY TO FUMONISIN B1 IN SOIL. Toxicologist. v.77. Abstract. p. 189. Interpretive Summary: abstract only
Technical Abstract: Fumonisins (FB) are water soluble mycotoxins produced by F. verticillioides, which is parasitic to corn plants. FBs are inhibitors of ceramide synthase. While FB1 is not known to cause plant disease in the field, it is found in the ear, roots, and stalks of corn. FB1 in corn debris can be leached by rainfall and can move through soils intact. However, a large amount is bound in certain soils. In sandy loam soils, FB1 can be released under acid conditions. These data suggest that FB1 from corn debris, or produced by F. verticillioides in the soil, can accumulate in soil and under certain environmental conditions the FB1 could be released and become biologically available. The objectives of this study were to determine: i) can F. verticillioides produce FB1 in soil, ii) is the FB1 in soil biologically active, and iii) is FB1 in soil toxic to corn seedlings. Corn seeds were inoculated with spore suspensions from pathogenic or non-pathogenic strains of F. verticillioides. Seedlings were grown for 21 days in potting soil. The roots and soil were analyzed for sphingoid bases (a marker of ceramide synthase inhibition) and FB1, respectively. Only seedlings inoculated with the pathogenic strain had elevated levels of sphinganine and the degree of elevation was correlated with the severity of the pathology. FB1 was only detected in soil from the plants inoculated with the pathogenic strain. In a second experiment surface sterilized seeds were planted and watered for six days with of 1, 5, or 10 ppm FB1 and grown for 15 more days. The FB1 in soil and the sphinganine in roots were closely correlated with the FB1 dosage. Reduced root mass was noted at 10 ppm. These results show that under laboratory conditions i) FB1 can be produced by F. verticillioides in soil, ii) the soil FB1 taken up by plants is biologically active, and iii) FB1 in soil can have adverse effects on plants. Thus, providing proof in principle that FB1 in soil can cause corn seedling disease.