title: High-lysine corn generated by endosperm-specific suppression of lysine catabolism using RNAi.
abstract: Because of the limited lysine content in corn grain, synthetic lysine supplements are added to corn meal-based rations for animal feed. The development of biotechnology, combined with the understanding of plant lysine metabolism, provides an alternative solution for increasing corn lysine content through genetic engineering. Here, we report that by suppressing lysine catabolism, transgenic maize kernels accumulated a significant amount of lysine. This was achieved by RNA interference (RNAi) through the endosperm-specific expression of an inverted-repeat (IR) sequence targeting the maize bifunctional lysine degradation enzyme, lysine-ketoglutarate reductase/saccharopine dehydrogenase (ZLKR/SDH). Although plant-short interfering RNA (siRNA) were reported to lack tissue specificity due to systemic spreading, we confirmed that the suppression of ZLKR/SDH in developing transgenic kernels was restricted to endosperm tissue. Furthermore, results from our cloning and sequencing of siRNA suggested the absence of transitive RNAi. These results support the practical use of RNAi for plant genetic engineering to specifically target gene suppression in desired tissues without eliciting systemic spreading and the transitive nature of plant RNAi silencing.
authors.affiliation: Mystic Research, Monsanto Company, 62 Maritime Drive, Mystic, CT 06355, USA.
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Houmard
authors.forename: Jonnelle L
authors.initials: JL
authors.lastname: Mainville
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Bonin
authors.forename: Shihshieh
authors.initials: S
authors.lastname: Huang
authors.forename: Michael H
authors.initials: MH
authors.lastname: Luethy
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Malvar
mesh_terms: D015152:Blotting, Northern; D015153:Blotting, Western; D018506:Gene Expression Regulation, Plant; D005822:Genetic Vectors / Q000235:genetics; D008239:Lysine / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012443:Saccharopine Dehydrogenases / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000378:metabolism; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; C108912:endosperm specific protein, Zea mays; D012443:Saccharopine Dehydrogenases; D008239:Lysine