No description available.

Major interest has focused on the identification of regulatory factors involved in lipid biosynthesis. This study examined the B.napus β-Keto-ACP reductase 5' sequence for potential regulatory cis-acting elements. The 5' sequence of the most highly expressed Brassica napus β-Keto-ACP reductase isoform was fused to the reporter gene β-glucuronidase (GUS) and its expression pattern examined within transgenic Arabidopsis. The construct was shown to act as a functional promoter and direct transcription within embryos, cotyledons and roots. There was no apparent staining within the true leaves, but staining was visible within the cotyledons. Overlapping fragments of the promoter were analysed in gel mobility shift assays and all six showed the formation of protein-DNA complexes. Competition analysis suggested that the same trans-acting factor binds to a number of regions along the promoter. The protein-DNA complex appeared to be competed away by the Arabidopsis enoyl-ACP reductase (EnR) promoter sequence, but not the lipid transfer protein (LTP) promoter. A common 9bp cis-element (CGCANTAAA) was identified in four of the six promoter fragments. Deletion analysis of the β-Keto-ACP reductase promoter intransient expression experiments into B.napus tissue, suggested the promoter could still direct transcription upon deletion to 132bp within embryos. The GUS expression appeared to show more than one decrease in expression upon subsequent deletions of the promoter within embryos, suggesting that more than one cis-element may be involved in the control of transcription. At least one of these suspected decreases con elated with the deletion of one of the 9bp boxes identified. Differences were observed for expression of the constructs within leaves and embryos suggesting that different elements may be involved in transcriptional control within these tissues. The identification of a potential cis-acting element within this study could be used to isolate a potential regulatory trans-acting factor that binds to the B.napus β-Keto-ACP reductase promoter.

No description available.

CGI-58 is the defective gene in the human neutral lipid storage disease called Chanarin-Dorfman syndrome. This disorder causes intracellular lipid droplets to accumulate in nonadipose tissues, such as skin and blood cells. Here, disruption of the homologous CGI-58 gene in Arabidopsis thaliana resulted in the accumulation of neutral lipid droplets in mature leaves. Mass spectroscopy of isolated lipid droplets from cgi-58 loss-of-function mutants showed they contain triacylglycerols with common leaf specific fatty acids. Leaves of mature cgi-58 plants exhibited a marked increase in absolute triacylglycerol levels, more than 10-fold higher than in wild-type plants. Lipid levels in the oil-storing seeds of cgi-58 loss-of-function plants were unchanged, and unlike mutations in beta-oxidation, the cgi-58 seeds germinated and grew normally, requiring no rescue with sucrose. We conclude that the participation of CGI-58 in neutral lipid homeostasis of nonfat-storing tissues is similar, although not identical, between plant and animal species. This unique insight may have implications for designing a new generation of technologies that enhance the neutral lipid content and composition of corp plants.

Classically, endogenous fatty acid ethanolamides and their derivatives that bind to the cannabinoid receptors and trigger a signalling pathway are referred to as endocannabinoids. Although derivatives of arachidonic acid, including arachidonylethanolamine or anandamide, are the known endogenous ligands for cannabinoid receptors, other fatty acid ethanolamides or N-acylethanolamines (NAE) that vary in carbon chain length and saturation occur ubiquitously in eukaryotic organisms and play an important role in their physiology and development. The metabolic pathway for NAEs is highly conserved among eukaryotes and well characterised in mammalian systems. Although NAE pathway is only partly elucidated in plants, significant progress has been made in the past 20 years in understanding the implications of the metabolism of saturated and unsaturated endocannabinoid-like molecules in plant development and growth. The latest advancements in the field of plant endocannabinoid research are reviewed. Key Concepts Endocannabinoids are endogenous ligands of cannabinoid receptors in mammalian systems. Endocannabinoids belong to a class of small bioactive lipid molecules that are derivatives of fatty acids including their ethanolamides, referred to as N-acylethanolamines. N-Acylethanolamines are ubiquitous and their metabolic pathway is highly conserved among eukaryotes. In higher plants, only 12–18C N-acylethanolamines have been identified and their metabolic pathway is partly elucidated. The endocannabinoid-like lipids play an important role in seed germination, seedling development, flowering and cellular organisation. In plants, N-acylethanolamines also participate in mediating responses to biotic and abiotic stress.

In this study, I examined the use of mouse (Mus musculus) Fat Specific Protein 27 (FSP27) ectopically expressed in Arabidopsis thaliana and Nicotiana benthamiana as a means to increase lipid droplet (LD) presence in plant tissues. In mammalian cells, this protein induces cytoplasmic LD clustering and fusion and helps prevent breakdown of LDs contributing to the large, single LD that dominates adipocytes. When expressed in Arabidopsis thaliana and Nicotiana benthamiana, FSP27 retained its functionality and supported the accumulation of numerous and large cytoplasmic LDs, although it failed to produce the large, single LD that typifies adipose cells. FSP27 has no obvious homologs in plants, but a search for possible distant homologs in Arabidopsis returned a Tudor/PWWP/MBT protein coded for by the gene AT1G80810 which for the purposes of this study, we have called LIPID REGULATORY TUDOR DOMAIN CONTAINING GENE 1 (LRT1). As a possible homolog of FSP27, LRT1 was expected to have a positive regulatory effect on LDs in cells. Instead, a negative regulatory effect was observed in which disruption of the gene induced an accumulation of cytoplasmic LDs in non-seed tissue. A study of lrt1 mutants demonstrated that disruption this gene is the causal factor of the cytoplasmic LD accumulation observed in the mutants, that this phenotype occurs in above ground tissues and is present throughout the early growth stages of the plant. Further examination of lrt1 mutant plants has allowed a preliminary understanding of the role LRT1 may play in LD regulation. Taken together, the results of this study point towards some promising strategies to increase LD content in plant tissues.