期刊
PLANT JOURNAL
卷 89, 期 2, 页码 278-290出版社
WILEY
DOI: 10.1111/tpj.13382
关键词
glycosyl inositol phosphorylceramides; glucuronosyltransferase; IPUT1; sphingolipid; pollen tube growth; Arabidopsis thaliana
资金
- U.S.Department of Energy, Office of Science, Office of Biological and Environmental Research [DE-AC02-05CH11231]
- National Science Foundation [MCB-1158500]
- Life Sciences Research Foundation fellowship from the Gordon and Betty Moore Foundation
- Direct For Biological Sciences
- Div Of Molecular and Cellular Bioscience [1158500] Funding Source: National Science Foundation
Sphingolipids are a major component of plant plasma membranes and endomembranes, and mediate a diverse range of biological processes. Study of the highly glycosylated glycosyl inositol phosphorylceramide (GIPC) sphingolipids has been slow as a result of challenges associated with the extractability of GIPCs, and their functions in the plant remain poorly characterized. We recently discovered an Arabidopsis GIPC glucuronosyltransferase, INOSITOL PHOSPHORYLCERAMIDE GLUCURONOSYLTRANSFERASE 1 (IPUT1), which is the first enzyme in the GIPC glycosylation pathway. Plants homozygous for the iput1 loss-of-function mutation were unobtainable, and so the developmental effects of reduced GIPC glucuronosylation could not be analyzed in planta. Using a pollen-specific rescue construct, we have here isolated homozygous iput1 mutants. The iput1 mutants show severe dwarfism, compromised pollen tube guidance, and constitutive activation of salicyclic acid-mediated defense pathways. The mutants also possess reduced GIPCs, increased ceramides, and an increased incorporation of short-chain fatty acids and dihydroxylated bases into inositol phosphorylceramides and GIPCs. The assignment of a direct role for GIPC glycan head groups in the impaired processes in iput1 mutants is complicated by the vast compensatory changes in the sphingolipidome; however, our results reveal that the glycosylation steps of GIPC biosynthesis are important regulated components of sphingolipid metabolism. This study corroborates previously suggested roles for GIPC glycans in plant growth and defense, suggests important roles for them in reproduction and demonstrates that the entire sphingolipidome is sensitive to their status.
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