Distribution and molecular profile of betaine lipids in Basidiomycete fungi.

Betaine lipids are non-phosphorus glycerolipids found across diverse organisms, including bacteria, algae, ferns, and certain fungi, and are capable of substituting phospholipids under phosphate deficiency. Their distribution in the Basidiomycota division of fungi remains enigmatic. This study presents the first comprehensive survey of diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) distribution in both natural fruiting bodies and pure cultures of over 150 fungal species. Comparative lipid analysis of fungal mycelium grown on complete versus phosphorus-depleted media revealed that DGTS biosynthesis is predominantly a non-constitutive process that depends on the availability of phosphorus. HPLC-MS/MS lipidomics enabled the identification of 55 molecular species of DGTS and demonstrated that the molecular profile of DGTS markedly differs from other membrane glycerolipids by pronounced enrichment in odd-chain fatty acids, particularly 15:0 and 17:0. DGTS primarily comprises fatty acid combinations of 16- and 18-carbon chains, in contrast to phosphatidylcholine (PC), which is predominantly esterified with two 18-carbon moieties. Notably, neither phylogenetic relationships nor ecological traits of the fungal species correlate strongly with DGTS presence or molecular profile, suggesting that its distribution is governed primarily by lineage-specific evolutionary events rather than adaptive pressures.