No abstract

Very long chain fatty acids (VLCFAs) are essential lipid components in many plants. 3 Ketoacyl CoA synthase (KCS) catalyzes the condensation reaction to form 3 ketoacyl CoA in VLCFA synthesis. AtELO4 has been reported to be involved in VLCFA synthesis, functioning as a KCS in Arabidopsis. However, no stud ies on other three AtELO members have been reported. Here, we initially found by real time PCR in Arabi dopsis thaliana (L.) Heynh. that AtELO1, AtELO3, and AtELO4 displayed characteristic expression patterns, but AtELO2 was nearly expressed in any organ. Then the transient expression of ELO like eGFP fusions in Arabidopsis green leaf protoplasts showed that AtELO1, AtELO3, and AtELO4 were localized in the endo plasmic reticulum (ER), where VLCFA synthesis took place. Finally, we found that the contents of all fatty acids were decreased by 10-20% in seeds of atelo1 T DNA insertion mutants. In seeds of Pro35S:AtELO1 plants, the levels of all remaining components, except C20:0 and C20:3, were significantly increased. Taken together, our study revealed biological functions of AtELO members and might lay the foundation for further genetic manipulations to generate oil crops with the high oil content.

Palmitoylation is a reversible posttranslational addition of palmitate to cysteine residues in proteins through a thioester bond by a family of DHHC (Asp-His-His-Cys) palmitoyltransferases (PATs) involved in cellular signaling, membrane trafficking, and synaptic transmission. There are 20 genes containing DHHC domain predicted to encode putative palmitoyltransferase in Arabidopsis thaliana genome. However, little is known about their characteristics such as genetic relationship and expression profile. Here, we present an overview of the putative PAT genes in A. thaliana focusing on their phylogeny gene structure and expression profiles in different tissues and under different stresses. Besides conserved DHHC domain, the identity of their cDNA sequences was from 30 to 60%. Temprospatial expression profile of each putative gene of the entire PAT family showed that nineteen of twenty putative PAT members differently expressed in flowers, leaves, stems, roots, seedlings, young and old siliques except At2g40990. Among these nineteen expressed putative PATs, some members expressed at very high levels in certain tissue and some exhibited more even distribution in different tissues. This is the first report on the expression patterns of all these putative PAT genes, which will provide important fundamental data for further identification of their biological functions.