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Title: Accumulation of sphingoid bases and sphingoid base 1-phosphates: A possible mechanism for Fusarium verticillioides corn-seedling disease

Author
item WILLIAMS, LONNIE - Former ARS Employee
item Glenn, Anthony - Tony
item Bacon, Charles
item SMITH, M - University Of Georgia
item Riley, Ronald

Submitted to: Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop-The Peanut Foundation
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2004
Publication Date: 12/31/2004
Citation: Williams, L.D., Glenn, A.E., Bacon, C.W., Smith, M.A., Riley, R.T. 2004. Accumulation of sphingoid bases and sphingoid base 1-phosphates: A possible mechanism for Fusarium verticillioides corn-seedling disease. Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop-The Peanut Foundation. p. 10.

Interpretive Summary:

Technical Abstract: Sphingolipids are important structural components of membranes involved in signaling pathways that regulate cell growth and death. Fumonisins (FB) are water soluble mycotoxins produced by F. verticillioides, which is parasitic to corn. FBs are inhibitors of ceramide synthase (CS), a key enzyme in sphingolipid biosynthesis. Inhibition of CS causes an increase in sphinganine and sphingosine (phytosphingosine in plants), as well as their respective 1-phosphates, which is used as a biomarker for FB activity. While FB is not known to cause plant disease in the field, it is found in the ear, roots, and stalks of corn. The objectives of this study were to determine the dose- and time-dependent effects of FB1 in soils on i) root development and ii) disruption of sphingolipid metabolism in roots. Sterilized corn seeds were germinated and planted in sterile potting soil (10/pot) and watered with solutions of FB1 (0, 1, 5, 10, and 20 µg/ml). The seedlings were dosed with FB1 on days 2, 4, and 6 after planting, followed by ddH2O as needed until harvest. The experiment was split into two time groups (3 reps per dose), the first group was harvested on day 8 and the second group was harvested on day 21. There was a dose dependent reduction in root mass in the 21 day time group at 5, 10, and 20 µg/ml FB1, while there was a slight increase in root growth at 1 µg/ml FB1. FB1 was detected in the soils as well as the roots, and the levels were closely correlated with the FB1 dosage. There was a dose dependent elevation in sphingoid bases and their 1-phosphates in the root tissues from both time groups. These results show that under laboratory conditions FB1 in soils can i) affect root growth and alter seedling performance, ii) FB1 in soil can be taken up by roots, iii) FB1 in soils can cause marked dose-dependent elevation in sphingoid bases and their 1-phosphates that precede reduced root growth.