Abstract
Fumonisin B1 (FB1) elicits a programmed cell death (PCD) in plants, probably through competitive inhibition of sphingosine-N-acyltransferase. Because this inhibition results in the accumulation of free sphingoid bases in cells, to evaluate the cellular effects of free sphingoid bases involved in the PCD, functional characterization of enzymes that control the intracellular levels of sphingoid bases is very important. Degradation of sphingoid bases proceeds from two specific enzymatic steps. Sphingoid bases are first phosphorylated at the 1-hydroxy group to form sphingoid base 1-phosphate, and then cleaved to a long-chain aldehyde and ethanolamine-phosphate. Sphingosine-1-phosphate lyase (SPL) is a cleavage enzyme responsible for the ultimate step in sphingolipid catabolism. Here we observed that Arabidopsis SPL T-DNA mutants are sensitive to FB1. Mechanisms of the sensitivity will be discussed with several data in this communication.
