Sphingoid long-chain base composition of glucosylceramides in Fabaceae: a phylogenetic interpretation of Fabeae.

The sphingoid long-chain base (LCB) composition of glucosylceramides was characterized in 31 species of Fabaceae including the model legumes Lotus japonicus and Medicago truncatula. With the exception of Lupinus texensis L, the 8-trans/cis-unsaturated isomers of 4-hydroxy-8-sphingenines [i.e., t18:1 (8t) plus t18:1 (8c)] were the major components in each species. In tribe Fabeae, each species from four genera--Pisum, Lathyrus, Lens, and Vicia--showed that more than 50% of dihydroxy sphingoid LCBs are 8-sphingenines [i.e., d18:1 (8t) plus d18:1 (8c)]. These results suggest that the sphingoid LCB composition of glucosylceramides reflects the phylogenetic relationships within the Fabeae.

Degradation of sphingoid long-chain base 1-phosphates (LCB-1Ps): functional characterization and expression of AtDPL1 encoding LCB-1P lyase involved in the dehydration stress response in Arabidopsis.

Sphingoid long-chain base (LCB) 1-phosphates are degradated by LCB 1-phosphate lyase to C(16) fatty aldehydes and phosphoethanolamine. Here, we confirmed that the At1g27980 gene product, AtDPL1, is a functional LCB-1-phosphate lyase. Expression of green fluorescent protein fusion products in suspension-cultured Arabidopsis cells showed that AtDPL1 is located to the endoplasmic reticulum. The rates of fresh weight decreases of dpl1-1 and dpl1-2 mutants were significantly slower than those of the wild-type plants. This ability to limit their transpiration reflected the leaf temperature of the mutant plants more than that of wild-type plants, suggesting that AtDPL1 plays a role in dehydration stress.