Abstract
In seeds, the subcellular storage oil bodies have a matrix of oils (triacylglycerols) surrounded by a layer of phospholipids embedded with abundant structural proteins called oleosins. We used two maize (Zea mays L.) strains having diverse kernel (seed) oil contents to study the effects of varying the oil and oleosin contents on the structure of the oil bodies. Illinois High Oils (IHO, 15% w/w oils) and Illinois Low Oils (ILO, 0.5%) maize kernels were the products of breeding for diverse oil contents for about 100 generations. In both maize strains, although the genes for oil synthesis had apparently been modified drastically, the genes encoding oleosins appeared to be unaltered, as revealed by Southern blot analyses of the three oleosin genes and sodium dodecyl sulfate-polyacrylamide gel electrophoresis with immunoblotting of the oleosins. In addition, both strains contained the same three oleosin isoforms of a defined proportion, and both accumulated oils and oleosins coordinately. Oleosins in both strains were restricted to the oil bodies, as shown by analyses of the various subcellular fractions separated by sucrosedensity-gradient centrifugation. Electron microscopy of the embryos and the isolated organelles revealed that the oil bodies in IHO were larger and had a spherical shape, whereas those in ILO were smaller and had irregular shapes. We conclude that in seeds, oleosin genes are expressed independent of the oil contents, and the size and shape of the oil bodies are dictated by the ratio of oils to oleosins synthesized during seed maturation. The extensive breeding for diverse oil contents has not altered the apparent mechanism of oil-body synthesis and the occurrence of hetero-dimer or -multimer of oleosin isoforms on the oil bodies.
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Abbreviations
- IHO:
-
Illinois High Oils
- ILO:
-
Illinois Low Oils
References
Burr FA, Burr B (1983) Slab gel system for the resolution of oligopeptides below molecular weight of 10000. Methods Enzymol 96: 239–244
Cao YZ, Huang AHC (1986) Diacylglycerol acyltransferase in maturing oil seeds of maize and other species. Plant Physiol 82: 813–820
Dellaporta SL, Wood J, Hicks JB (1983) A plant DNA minipreparation: Version II. Plant Mol Biol Rep 1: 19
Dittmer JC, Wells MA (1969) Quantitative and qualitative analysis of lipids and lipid components. Methods Enzymol 14: 482–531
Dudley JW, Lambert RJ (1992) 90-Generations of selection for oil and protein in maize. Maydica 37: 81–87
Hatzopoulos P, Franz G, Choy L, Sung RZ (1990) Interaction of nuclear factors with upstream sequences of a lipid body membrane protein gene from carrot. Plant Cell 2: 457–467
Huang AHC (1992) Oil bodies and oleosins in seeds. Annu Rev Plant Physiol Plant Mol Biol 43: 177–200
Karnovsky MJ (1965) A formaldehyde/glutaraldehyde fixative of high osmolarity for use in electron microscopy. J Cell Biol 27: 137A
Lee K, Huang AHC (1994) Genes encoding oleosins in maize kernel of inbreds Mol7 and B73. Plant Mol Biol 26: 1981–1987
Lee K, Ratnayake C, Huang AHC (1995) Genetic dissection of the co-expression of genes encoding the two isoforms of oleosins in the oil bodies of maize kernel. Plant J 7: 603–611
Murphy DJ, Keen JN, O'Sullivan JN, Au DMY, Edwards EW, Jackson PJ, Cummins I, Gibbons T, Shaw CH, Ryan AJ (1991) A class of amphipathic proteins associated with lipid storage bodies in plants. Possible similarities with animal serum apolipoproteins. Biochim Biophys Acta 1088: 86–94
Qu R, Huang AHC (1990) Oleosin KD18 on the surface of oil bodies in maize. Genomic and cDNA sequences and the deduced protein structure. J Biol Chem 265: 2238–2243
Smith PK, Krohn RI, Hermanson GT, Malia AK, Gartner FH, Proverzano MD, Fujimoto EK, Goeke NM, Olson BJ, Klenk DC (1985) Measurement of protein using bicinchoninic acid. Anal Biochem 150: 76–85
Spurr AR (1969) A low viscosity epoxy resin embedding medium for electron microscopy. J Ultrastruct Res 26: 31–43
Steer MW (1981) Understanding Cell Structure. Cambridge University Press, Cambridge, UK
Trelease RN (1969) Changes and characteristics of lipid bodies during development. PhD thesis, University of Texas at Austin, USA
Tzen JTC, Cao YZ, Laurent P, Ratnayake C, Huang AHC (1993) Lipids, proteins, and structure of seed oil bodies from diverse species. Plant Physiol 101: 267–276
Tzen JTC, Huang AHC (1992) Surface structure and properties of plant seed oil bodies. J Cell Biol 117: 327–335
Tzen JTC, Lai YK, Chan KL, Huang AHC (1990) Oleosin isoforms of high and low molecular weights are present in the oil bodies of diverse seed species. Plant Physiol 94: 1282–1289
Tzen JTC, Lie GC, Huang AHC (1992) Characterization of the charged components and their topology on the surface of plant seed oil bodies. J Biol Chem 267: 15626–15634
Vance VB, Huang AHC (1987) The major protein from lipid bodies of maize: characterization and structure based on cDNA cloning. J Biol Chem 262: 11275–11279
Wang SM, Huang AHC (1987) Biosynthesis of lipase in the scutellum of maize kernel. J Biol Chem 262: 2270–2274
Wang SM, Lin YH, Huang AHC (1984) Lipase activities in scutella of maize lines having diverse kernel lipid content. Plant Physiol 76: 837–839
Wilson MB, Nakane PK (1978) Recent development in the periodate method of conjugating horseradish peroxidase (HRPO) to antibodies. In: Knapp W, Holubar K, Wick G (eds) Immunofluorescence and related staining techniques. Elsevier/North Holland Biomedical Press, Amsterdam, pp 215–224
Yatsu LY, Jacks TL (1972) Spherosome membranes. Half unitmembranes. Plant Physiol 49: 937–943
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This work was supported by a USDA NRICGP grant. We thank Dr. J.W. Dudley of the University of Illinois for the IHO and ILO maize kernels, and Dr. W. Thomson for discussion on the stereological method.
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Ting, J.T.L., Lee, K., Ratnayake, C. et al. Oleosin genes in maize kernels having diverse oil contents are constitutively expressed independent of oil contents. Planta 199, 158–165 (1996). https://doi.org/10.1007/BF00196892
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DOI: https://doi.org/10.1007/BF00196892