Triacylglycerols (TAGs) are stored in variable amounts (1-90 % by dry weight) in seed and non-seed tissues of various plant species. To gain insights into tissue- and species-specific regulation and biosynthesis of TAG in plants, we used 454 pyro and Illumina sequencing and generated transcriptome for eight species (brassica, castor, nasturtium, euonymus, oil palm, date palm, and avocado). In all tissues analyzed, an increased expression was noted for genes mostly associated with fatty acid biosynthesis in plastid, but much less increase in those for TAG assembly in the endoplasmic reticulum. Furthermore, hexose metabolism in plastid, relative to cytosol, appeared to be crucial in most oil-rich tissues, which is likely associated with directing high pyruvate flux toward plastid fatty acid synthesis. We also identified that WRINKLED1 transcription factor acts as a master switch in regulating oil biosynthesis in most oil-rich seed and non-seed tissues of monocot and dicot plants, suggesting a highly conserved mechanism. Overall, our studies point to distinctive modes of regulation of fatty acid biosynthesis and TAG assembly that are conserved in both seed and non-seed oil-rich plants, which can be extended to other crops for the purpose of generating biofuels.