Sphingolipid Δ4-desaturation is an important metabolic step for glycosylceramide formation in Physcomitrium patens

J Exp Bot. 2021 Jul 28;72(15):5569-5583. doi: 10.1093/jxb/erab238.

Abstract

Glycosylceramides are abundant membrane components in vascular plants and are associated with cell differentiation, organogenesis, and protein secretion. Long-chain base (LCB) Δ4-desaturation is an important structural feature for metabolic channeling of sphingolipids into glycosylceramide formation in plants and fungi. In Arabidopsis thaliana, LCB Δ4-unsaturated glycosylceramides are restricted to pollen and floral tissue, indicating that LCB Δ4-desaturation has a less important overall physiological role in A. thaliana. In the bryophyte Physcomitrium patens, LCB Δ4-desaturation is a feature of the most abundant glycosylceramides of the gametophyte generation. Metabolic changes in the P. patens null mutants for the sphingolipid Δ4-desaturase (PpSD4D) and the glycosylceramide synthase (PpGCS), sd4d-1 and gcs-1, were determined by ultra-performance liquid chromatography coupled with nanoelectrospray ionization and triple quadrupole tandem mass spectrometry analysis. sd4d-1 plants lacked unsaturated LCBs and the most abundant glycosylceramides. gcs-1 plants lacked all glycosylceramides and accumulated hydroxyceramides. While sd4d-1 plants mostly resembled wild-type plants, gcs-1 mutants were impaired in growth and development. These results indicate that LCB Δ4-desaturation is a prerequisite for the formation of the most abundant glycosylceramides in P. patens. However, loss of unsaturated LCBs does not affect plant viability, while blockage of glycosylceramide synthesis in gcs-1 plants causes severe plant growth and development defects.

Keywords: Physcomitrium patens; Glycosylceramide; glycosylceramide synthase; long-chain base desaturation; non-vascular plants; plant development; sphingolipid metabolism; sphingolipid Δ4-desaturase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis Proteins* / genetics
  • Arabidopsis* / genetics
  • Bryopsida*
  • Pollen
  • Sphingolipids

Substances

  • Arabidopsis Proteins
  • Sphingolipids