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Title:   Author  item
                                            JIA, HONGWU - ISUitem
                                            NETTLETON, DAN - ISUitem
                                            Scott, Marvin
  Submitted to: Maize Genetics Conference Abstracts
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 3/13/2003
                                    Publication  Date: 3/13/2003
                                    Citation: JIA, H., NETTLETON, D., SCOTT, M.P. MICROARRAY ANALYSIS OF MAIZE OPAQUE2 IN DEVELOPING ENDOSPERMS OF EIGHT INBRED LINES. MAIZE GENETICS CONFERENCE ABSTRACTS. 2003. http://www.maizegdb.org/cgi-bin/displayrefrecord.cgi?id=885090.Interpretive Summary:
                                Technical Abstract: The Opaque2 (o2) mutation can significantly improve the protein nutritional quality of corn kernels by increasing the lysine content of maize endosperm. Since this discovery, it has been the subject of intense research. Studies conducted over the past 40 years have revealed that the o2 mutation reduces the synthesis of zein storage proteins and increases the level of free amino acids, including lysine. The biochemical and molecular mechanisms leading to these phenomena are only partially understood. We analyzed the grain from 5 inbred lines and their backcross o2 conversions and found that the extent of change in amino acid content of an o2 mutant is dependent on its genetic background. In recent years, high throughput microarray studies have been conducted to study the pattern of expression in normal and o2 mutant with a single genetic background. However, background-specific effects of o2 can obscure the main action of o2. In order to eliminate such marginal effects, we sought to identify genome-wide gene expression changes that are consistently maintained in the o2 mutant lines in several genetic backgrounds. Fourteen days after pollination, developing endosperms were harvested from eight pairs of near-isogenic lines. The pooled mRNA was labeled and hybridized to Unigene arrays from ZmDB. A duplicate dye-swap design was used for the microarray experiment and an ANOVA method was used to analyze the data. Our results showed that more than 80 genes are significantly down-regulated, including expected genes such as zeins and a pyruvate orthophospate dikinase, and a few are up-regulated significantly in o2 mutants. Further analysis will be done on these genes. In the future work, we hope to understand factors influencing amino acid content by studying global expression patterns of o2 at different developmental stages and o2 mutants from specific genetic backgrounds.


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