Investigation Of Subcellular Location Of Fatb As Well As Effects On ER And Golgi Due To FATB Disruption In Arabidopsis Thaliana

Lipids are not only the common chemical structures of cells, but also are thefundamental for cells to possess physiological activities. Fatty acids in the lipids playimportant roles in plant development, industry and agriculture. C16:0and C18:0fattyacyl-ACPs, which are produced in de novo fatty acid biosynthesis in plastids usingacetyl-CoA as building blocks, are hydrolyzed by fatty acyl thioesterases (FAT) to release freefatty acids for transport out of plastids in Arabidopsis thaliana. FAT plays important roles inlipid metabolism and plant development. FAT could be roughly divided into two groups,FATA and FATB, according to substrate preference. FATA family prefers unsaturated fattyacids, while FATB prefers saturated fatty acids.Subcellular localization of FAT is still lack. In this study, a full-length cDNA of fattyacyl-ACP thioesterase B (FATB) gene was cloned from Arabidopsis thaliana by RT-PCR. Wemade the construct fused with eGFP in transient expression vectorpUC-35s-FATB-eGFP-NOS, transformed above vector into Arabidopsis leaf protoplast anddetected fluorescence signals localized in chloroplasts under fluorescence microscope. Proteinsequence analysis using the DAS transmembrane prediction server classified FATB as anintegral membrane protein containing one transmembrane domain. Our work expands ourknowledge for investigation of molecular mechanisms for fatty acid transport outside plastids.Lipids are fundamental components of all cellular membrane systems. Reduced levels offatty acids could have significant effects on endocytic membrane trafficing. We find that thegrowth rate is reduced in the fatb mutant, and the mutant plant is dwarf. The morphology offatb mutant seeds reveal a range of deformed. In order to examine whether unbalanced ratioof saturated fatty acids to unsaturated fatty acids affects ER and Golgi morphology in fatbmutants, we obtained fatb mutant and wild-type plants containing ER marker GFP-HDEL andGolgi marker SF-GFP. The results observed under laser scanning confocal microscope indicated that the morphology of ER and Golgi in fatb mutants and wild-type plants did notshow any obvious differences. It is safe to make a conclusion that decreased saturated fattyacids outside plastids and unbalanced ratio between saturated and unsaturated fatty acids donot affect overall morphology of the ER and Golgi in fatb mutants. Our work provides aframe work for understanding correlation between intracellular organelle morphology withfatty acid profile.