Sphingolipids are ubiquitous and essential components of eukaryotic cells. They are major components of the membrane, and have also been identified to be important in signalling. Until recently, very little has been known about IPCS in plants. The activity has been characterized in bean microsomes in 2003 by Bromley et al., but until now no genes encoding IPCS have been identified. Here the three Arabidopsis thaliana genes potentially encoding IPCS, which is responsible for a step in sphingolipid synthesis have been characterized and the expression level has been identified. Genes have been cloned and transformed into the yeast-E. coli shuttle vector pRS426 MET for investigating the encoded activity. In vivo and metabolic labelling in vitro studies of the complementation studies of AURl of these IPCS genes demonstrated that IPCS function as AURl. Although salt tolerance in vivo studies and metabolic labelling in vitro studies of ISCl complementation studies showed that IPCS did not function as ISCl, IPC-PLC. By designing gene specific primer sets, tissue-specific expression patterns for these genes have been identified for the first time and suggest that the expression of particular IPCS genes are regulated in a tissue-specific and developmental stage manner. Furthermore, A. thaliana IPCS was found to be resistant to the anti-fungal agent aureobasidm A (AbA). This may provide important aspects to future management and prevention of fungal diseases in plants. Identifying the functions and characteristics of A. thaliana IPCS provides important aspects of sphmgolipid synthesis and signalling in plants
