Lipid Metabolism in Corn Tissue Culture and Molecular Biology of Soybean Seed Maturation

Abstract

127 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988.Lipid metabolism of corn (Zea mays) tissue culture was studied using seven strains or inbred lines. The lipid content from the embryogenic callus derived from these lines followed the same trend as the lipid content found in the seeds, however there was no consistent lipid pattern observed for the leaf or root callus from these same lines relative to the tissue that it originated from. Therefore corn embryogenic callus provides an ideal tissue to study lipid metabolism. Embryogenic calli were also used to select cell lines resistant to cerulenin, an inhibitor of fatty acid synthesis. While it was hypothesized that the cerulenin-resistant calli might be an overproducing-oil line, the selected resistant calli did not exhibit an increase in lipid content relative to the control calli.A variant corn callus induced from etiolated corn leaves from Illinois High Oil strain was identified. The variant callus has increased lipid content concomitant with increased acetyl-CoA carboxylase activity and altered biotin-containing protein patterns relative to the wild type callus. The variant callus also exhibited an altered fatty acid composition concomitant with decreased oleic acid desaturase activity. Thus it appears that acetyl-CoA carboxylase and oleic acid desaturase are important regulatory enzymes in lipid metabolism.Gene expression during precocious and natural maturation of soybean (Glycine max) seeds was investigated by cloning the cDNAs corresponding to the mRNAs which were expressed only during maturation. The cDNA clones were isolated by construction of a cDNA library from poly(A)\sp+RNA from four days pod dried 35 days after flowering (DAF) soybean seeds followed by differential hybridization. The soybean seed maturation polypeptide gene appears to be switched on in precociously dried immature (35 DAF) seeds or naturally maturing seeds. The maturation cDNA clones were shown to encode a 31 kD protein and this protein is encoded by a single copy or relatively low copy genes.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD