title: Identification and characterization of lysine-rich proteins and starch biosynthesis genes in the opaque2 mutant by transcriptional and proteomic analysis.
abstract: BACKGROUND
  The opaque2 mutant is valuable for producing maize varieties with enhanced nutritional value. However, the exact mechanisms by which it improves protein quality and creates a soft endosperm texture are unclear. Given the importance of improving nutritional quality in grain crops, a better understanding of the physiological basis for these traits is necessary.
  
  
  RESULTS
  In this study, we combined transcript profiling and proteomic analysis to better understand which genes and proteins are altered by opaque2 in the W64A inbred line. These analyses showed that the accumulation of some lysine-rich proteins, such as sorbitol dehydrogenase and glyceraldehyde3-phosphate dehydrogenase, was increased in mature kernels and may contribute substantially to the lysine content of opaque2 endosperm. Some defense proteins such as beta-glucosidase aggregating factor were strongly down regulated and may be regulated directly by opaque2. The mutant also had altered expression of a number of starch biosynthesis genes and this was associated with a more highly crystalline starch.
  
  
  CONCLUSIONS
  The results of these studies revealed specific target genes that can be investigated to further improve nutritional quality and agronomic performance of high lysine maize lines, particularly those based on the presence of the opaque2 mutation. Alteration of amylopectin branching patterns in opaque2 starch could contribute to generation of the soft, starchy endosperm.
authors.affiliation: Department of Biology, Baylor University, One Bear place #97388, Waco, TX 76798, USA.
authors.forename: Mo
authors.initials: M
authors.lastname: Jia
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
authors.forename: Kasi L
authors.initials: KL
authors.lastname: Clay
authors.forename: Rudolf
authors.initials: R
authors.lastname: Jung
authors.forename: Brian A
authors.initials: BA
authors.lastname: Larkins
authors.forename: Bryan C
authors.initials: BC
authors.lastname: Gibbon
mesh_terms: D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D056625:Endosperm / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008239:Lysine / Q000378:metabolism; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D040901:Proteomics; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D013213:Starch / Q000096:biosynthesis*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D003313:Zea mays / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D010940:Plant Proteins; D014157:Transcription Factors; C067402:opaque-2 protein, Zea mays; D013213:Starch; D008239:Lysine