Sphingolipids in plants: a guidebook on their function in membrane architecture, cellular processes, and environmental or developmental responses

Abstract

Sphingolipids are fundamental lipids involved in various cellular, developmental and stressresponse processes. As such, they orchestrate not only vital molecular mechanisms of living cells but also act in diseases, thus qualifying as potential pharmaceutical targets. Sphingolipids are universal to eukaryotes and are also present in some prokaryotes. Some sphingolipid structures are conserved between animals, plants and fungi, whereas others are found only in plants and fungi. In plants, the structural diversity of sphingolipids, as well as their downstream effectors and molecular and cellular mechanisms of action, are of tremendous interest to both basic and applied researchers, as about half of all small molecules in clinical use originate from plants. Here we review recent advances towards a better understanding of the biosynthesis of sphingolipids, the diversity in their structures as well as their functional roles in membrane architecture, cellular processes such as membrane trafficking and cell polarity, and cell responses to environmental or developmental signals.

Sphingolipids mediate polar sorting of PIN2 through phosphoinositide consumption at the trans-Golgi network

“…SLs display a wide structural diversity and contain several subclasses of lipids, including free Long Chain Bases (LCBs) that can be amidified with VLCFAs to produce VLCFA-ceramides on which an inositolphosphate group is added to generate inositolphosphorylceramide (IPC) 37 . IPC is further glycosylated to produce glycosyl-inositolphosphorylceramide (GIPC), the most abundant form of SLs in plants 36 , 37 (Fig. 6a ).…”

“…Interestingly, the sorting of the auxin efflux carrier PIN1, but not PIN2, has been shown to be dependent on VLCFAs of ceramides at RAB-A2a-positive/CCVs compartments 38 . Thus, it is reasonable to assume that different species of sphingolipids would be differentially distributed between SVs and CCVs of TGN and be involved in distinct sorting mechanisms 37 . The localization of IPCS enzymes at SVs would be a way to segregate these mechanisms.…”

Sweet Modifications Modulate Plant Development

“…Sphingolipids are omnipresent in eukaryotes and even occur in some bacteria [ 368 ]. Despite their widespread occurrence in eukaryotes, the molecular moieties of the sphingolipids differ between kingdoms [ 369 , 370 ]. For example, glycosyl inositol phosphoryl ceramides (GIPCs) are restricted to plants, fungi and some protozoans [ 371 ], while the glucosylceramides (GlcCERs) are common in all eukaryotes [ 369 , 372 ].…”

“…Generally, plant sphingolipids are classified into four major groups: ceramides, GlcCERs, GIPCs and free long chain bases [ 373 , 375 ]. In the last few decades, the plant sphingolipids were studied in more detail [ 370 , 372 , 377 ]. These molecules occur in the plasma membrane, tonoplast and other endomembranes [ 378 ].…”

“…Knock-out mutants of the genes responsible for the glycosylation of sphingolipids such as GlcCER synthase and inositol phosphorylceramide glucuronosyl transferase 1 are lethal or result in changed phenotypes. These knock-out mutants highlight the importance of the glycosylation of sphingolipids [ 370 ]. The processes involved in the biosynthesis of plant sphingolipids are beyond the scope of this review.…”