Synthesis and degradation of long-chain base phosphates affect fumonisin Bsub(1)-induced cell death in Arabidopsis thaliana
2017
Yanagawa, D. ((Konan University, Kobe (Japan). Graduate School of Natural Science, Department of Biology), (Konan University, Kobe (Japan). The Institute for Integrative Neurobiology)) | Ishikawa, T. | Imai, H.
Fumonisin Bsub(1) (FBsub(1)), an inducer of cell death, disrupts sphingolipid metabolism; large accumulations of de novo synthesized free long-chain bases (LCBs) are observed. However, it remains unclear whether tolerance to FBsub(1) toxicity in plants is connected with preventing the accumulation of free LCBs through their phosphorylation. Here a workflow for the extraction, detection and quantification of LCB phosphates (LCBPs) in Arabidopsis thaliana was developed. We studied the effect of expression of genes for three enzymes involved in the synthesis and degradation of LCBPs, LCB kinase (LCBK1), LCBP phosphatase (SPP1) and lyase (DPL1) on FBsub(1)-induced cell death. As expected, large accumulations of saturated free LCBs, dihydrosphingosine and phytosphingosine, were observed in the FBsub(1)-treated leaves. On the other hand, a high level of sphingenine phosphate was found in the FBsub(1)-treated leaves even though free sphingenine was found in low amounts in these leaves. In comparison of WT and spp1 plants, the LCBP/LCB ratio is likely to be correlated with the degree of FBsub(1)-induced cell death determined by trypan blue staining. The FBsub(1)-treated leaves in dpl1 plants showed severe cell death and the elevation of free LCBs and LCBPs. LCBK1-OX and -KD plants showed resistance and sensitivity to FBsub(1), respectively, whereas free LCB and LCBP levels in FBsub(1)-treated LCBK1-OX and -KD plants were moderately different to those in FBsub(1)-treated WT plants. Overall, the findings described here suggest that LCBP/LCB homeostasis is an important topic that participates in the tolerance of plant cells to FBsub(1).
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