Molecular cloning and characterization of a serine palmitoyltransferase gene from rice ( Oryza sativa ) and its gene expression in defense response to brown planthopper

To understand potential mechanisms involved in sphingolipids and their metabolic precursors, longchain bases (LCBs)-mediated stress response, we cloned rice LCB genes that encode serine palmitoyltransferase (SPT), which is the key enzyme of sphingolipid de novo biosynthesis. The full-length cDNAs of three LCB1 and three LCB2 genes were amplified by reverse transcription-polymerase chain reaction (RT-PCR). The lengths of the deduced LCB proteins ranged from 481 to 497 amino acid residues. Bioinformatics and comparative studies revealed that the polypeptide proteins had high homology in a large number of species from bacteria to humans. In rice, we found that OsLCB2a1 expression was up-regulated when infested by brown planthopper (BPH). Compared with other varieties, gene expression levels were higher in BPH-resistant varieties such as Mudgo and IR64. Gene expression was negatively correlated with BPH-resistant scores. Among different plant parts of rice varieties, gene expression was found to be significantly increased in the leaf blade of IR64 and the leaf sheath of Taiping. The mRNA level of OsLCB2a1 was found to be high at the maximum tillering stage of BPH-resistant varieties, suggesting that this gene may play a role in the vegetative stages of rice.