ANALYSIS OF ZEIN GENE EXPRESSION IN MAIZE

玉米醇溶蛋白基因编码种子贮藏蛋白。 玉米醇溶蛋白占胚乳蛋白的60%，由四种蛋白质组成。 结构上不同的类型：贫硫的α-玉米醇溶蛋白，和 富含硫的β、γ和δ-玉米醇溶蛋白。 α-玉米醇溶蛋白编码 一个可能有75到100个基因的多基因大家族，而β， γ和δ-玉米醇溶蛋白各自仅由一个或两个基因编码。 一 已经确定了一些突变，这些突变导致 α-玉米醇溶蛋白的合成。 其中至少有一个，opaque-2， 一种转录调节蛋白， 玉米醇溶蛋白基因家族的某些成员。 然而，机制 这些突变中的大多数通过其影响特定玉米醇溶蛋白的表达 不被理解。 关于编码这些基因的调控知之甚少。 富含硫的玉米醇溶蛋白。 最近，我们发现了一组基因， opaque-2 '修饰符。“改良的”不透明玉米系含有两种至 是标准opaque-2突变体的四倍。 的 “修饰基因”似乎是显性基因， γ-玉米醇溶蛋白基因的表达。 我们建议： (1)确定opaque-2 '修饰符”如何影响 γ-玉米醇溶蛋白基因 (2)调查遗传复杂性的不透明-2“修改器'和开始 来识别和分离修饰基因 (3)检验这一假设，即它是高含量的γ-玉米醇溶蛋白， 它的分布，负责玻璃体表型， 修改的不透明内核，以及 (4)进一步表征指导转录的DNA序列 α，β，γ-玉米醇溶蛋白 基因，并确定调节其转录的蛋白质。 除了扩大我们对组织特异性的理解， 基因表达，这些研究的结果将有应用， 提高玉米蛋白质和种子品质。

The zein genes of maize encode the seed storage proteins. Zeins constitute 60% of the endosperm protein and consist of four structurally distinct types: the sulfur-poor alpha -zeins, and the sulfur-rich beta, gamma, and delta -zeins. The alpha -zeins are encoded by a large multigene family of possibly 75 to 100 genes, while the beta, gamma, and delta -zeins are each encoded by only one or two genes. A number of mutations have been identified that cause a reduction in the synthesis of alpha -zeins. At least one of these, opaque-2, corresponds to a transcriptional regulatory protein that affects the expression of certain members of the alpha -zein gene family. However, the mechanisms by which most of these mutations affect the expression of specific zeins are not understood. Little is known about the regulation of the genes encoding the sulfur-rich zeins. Recently we characterized a group of genes called opaque-2 'modifiers.' The "modified' opaque lines of maize contain two to four times as much gamma zein as standard opaque-2 mutants. The "modifiers' appear to be dominant genes that specifically increase the expression of the gamma -zein genes. We propose to: (1) Determine how the opaque-2 'modifiers" affect the expression of gamma -zein genes (2) Investigate the genetic complexity of opaque-2 "modifiers' and begin to identify and isolate modifier genes (3) Test the hypothesis that it is the high content of gamma -zein and its distribution that are responsible for the vitreous phenotype of modified opaque kernels, and (4) Further characterize the DNA sequences that direct the transcription of alpha ,beta, and gamma -zein genes and identify the proteins regulating their transcription. In addition to expanding our understanding of tissue-specific gene expression, the results of these studies will have application to the improvement of maize protein and seed quality.