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Title: Translocation of sphingoid bases and their 1-phosphates, but not fumonisins, from roots to aerial tissues of maize seedlings watered with fumonisins.

item Zitomer, Nicholas
item JONES, SAMANTHA - South Carolina State University
item Bacon, Charles
item Glenn, Anthony - Tony
item Baldwin, Thomas
item Riley, Ronald

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2010
Publication Date: 6/23/2010
Citation: Zitomer, N.C., Jones, S., Bacon, C.W., Glenn, A.E., Baldwin, T.T., Riley, R.T. 2010. Translocation of sphingoid bases and their 1-phosphates, but not fumonisins, from roots to aerial tissues of maize seedlings watered with fumonisins. Journal of Agricultural and Food Chemistry. 58(12):7476-7481.

Interpretive Summary: Fumonisins are toxins produced by a fungus that infects corn plants. Our previous work showed that when corn seedlings were infected from seed by a fumonisin-producing fungus, one form of the fumonisin, fumonisin B1, moved up the plant significantly more than the other forms, fumonisin B2 and B3. The current experiment investigated this difference in movement up the plant by utilizing a watering system wherein the plants were exposed to fumonisin B1 alone, fumonisin B2 alone, or both together. By analyzing for the presence of the fumonisins in the plant roots and leaves, we were able to determine that neither fumonisin moved up the plant when introduced via watering, but both forms accumulated in root tissues, though to differing degrees. Our analyses also measured accumulation of biochemical markers of exposure to fumonisin, and, interestingly, it was found that those compounds did move up the plants. The biochemical markers accumulate as a result of fumonisin blockage of an enzyme that makes a unique type of fat known as sphingolipids. These results indicate that fungal infection is required for the fumonisins to be moved up into leaf tissues but that the sphingolipids that accumulate in roots move readily up the plant irregardless of fungal infection in the corn seedlings.

Technical Abstract: In an earlier study using maize seedlings grown from kernels inoculated with Fusarium verticillioides, fumonisin B1 (FB1) was preferentially accumulated in leaf tissue compared to FB2 and FB3. The present study tested whether maize seedlings preferentially translocate FB1 when plants are watered with FB1 and/or FB2, without the fungus present. The results show that neither FB1 nor FB2 was translocated when administered in the watering solution and while both FB1 and FB2 were taken up by the roots the accumulation of FB2 in roots was significantly less than predicted indicating that FB1 was preferentially accumulated. In addition there was clear evidence of ceramide synthase inhibition in the roots and sphingoid base and sphingoid base 1-phosphates accumulated in leaf tissue presumably due to translocation from the roots. These findings suggest that the fungal/plant interaction is necessary for FB1 translocation in maize seedlings infected with F. verticillioides.