Abstract
It has been well characterized that glycerol 3-phosphate (G3P) is exchanged with orthophosphate by the G3P permease (G3PP) in the inner membrane of Escherichia coli. Although no eukaryotic G3PPs have been identified so far, genes homologous to the bacterial G3PP are conserved among eukaryotes including higher plant. Arabidopsis has five G3PP homologs (AtG3PP1 to AtG3PP5), and according to the microarray database GENEVESTIGATOR, the expression of AtG3PP3 and AtG3PP4 are increased by salt, osmotic and cold stress. We reported in the T-DNA-insertional mutant g3pp4, germination of seeds was disturbed more severely than wild type under salt stress(Sakuma et al., 2008).
In this study, we further analyzed g3pp4 mutant together with g3pp3. Under osmotic stress with 300 mM mannitol, as well as under salt stress, g3pp4 mutant showed delayed and decreased germination. In addition, weight of g3pp4 mutant seeds was reduced by 21%, suggesting reduced oil content in seeds. In contrast, no clear difference was found between g3pp3 mutant and wild type. We will further investigate the involvement of AtG3PP4 in stress tolerance and lipid metabolism.
