The Function Analysis Of Ceramidase (CER) From Arabidopsis Thaliana

Sphingolipids content a ceramide backbone, which are one of complicated lipids, Sphingolipids and their derivants are a class of important singnal molecular in mammalian and yeast. The research of sphingolipids in plants has been explored only in recent years, Far less is known about sphingolipids functions in plants. However, increasingly investigations indicate that sphingolipids and their derivants have important signalling roles in plants as well. Ceramide is the basic structure of sphingolipids, who is in the center of metabolic patyway of sphingolipids, and is also the simplest sphingolipid. With the further investigation of sphingolipids in mammal and yeast, we found that besides are ubiquitous membrane components in eukaryotic cells and in a few bacteria, ceramide and their derivants as an important class of messenger molecules involved in many significant signal pathway, such as cell growth, reduplication, differentiation, senescence and apoptosis. Ceramide metabolism in intracellular was regulated many kinds of enzymes, and has reported several enzymes correlate with ceramide. Ceramidase hydrolyze ceramide into fatty acid and chain base, which is an important part in metabolic pathway of sphingolipids. The function of ceramidase in mammal and yeast remains elusive, and there are not any report about the function of ceramidase in plants. So this work uses Arabidopsis thaliana as material to study the function of ceramidase in plants.This work has identification 9 homozygosis single mutants of AtCER through PCR screening and Northern blot. The expression analysis of transgenic plants of AtCER promoter link to GUS report gene indicated that expression position of AtCER are located in root tips and vascular tissues in plants. Northern blot results show that many kinds of stress induce the expression of AtCER, such as ABA,SA,NaCl, manitol and 0℃. This essay also investigated the AtCER function in oxidative stress caused by H2O2. The leaves of AtCER mutants cerl, cer2 and cer3, exhibited more severe levels of yellowing and necrotic lesions than wild-type under H2O2 treatment. Further investigation by the physiological and biochemical methods, indicated that chlorophyll content of these mutants decreased 2 or 4-fold than wild-type, and their conductivity were increased significantly; the antioxidase activity in leaves of AtCER mutants was approximately 1.5 or 3-fold higher than wild-type after H2O2 treatment. All of those results suggested that AtCER may be involved in H2O2-induced Oxidative stress.