Characterization of the Narrow Sheath Duplicate Factor Pair: Pattern Forming Loci Involved in Maize Leaf Development

遗传和分子生物学的调查建议，以确定是否存在一个发育区室在玉米叶。 以前，细胞谱系分析和KNOX（标记的叶/非叶身份）的玉米分生组织的免疫定位表明，边缘域是不利用窄鞘突变体植物的叶创始细胞。 在成熟时，窄鞘突变体的叶非常窄，并且缺乏通常在玉米叶边缘发现的特定细胞和组织类型。 总之，这些数据表明，边缘域存在于玉米叶中，并且该植物区室可以通过重复基因窄鞘1和窄鞘2的活性在分生组织创始细胞阶段建立。 提出了三个项目，以测试是否叶缘的发展进行通过细分的创始人细胞到不同的发展领域，或者如果叶缘的图案晚得多的非区室化的方式。1）克隆镶嵌分析将被用来推断发育时间和组织层特异性的NS 2基因功能。 该分析还将确定NS 2活性是否局限于叶的边缘结构域或在其它叶区域中是必需的。2）将分离和测序对应于每个窄鞘基因的完整基因组和cDNA克隆。 序列分析将揭示ns 1和ns 2之间的结构同源性的程度，并可能建议它们的分子功能。3）北方分析，RNA原位杂交和免疫组织定位分析的Ns基因表达在整个叶发育将测试的假设，即玉米叶的边缘的模式在发育的创始细胞阶段的结构域特异性表达的Ns基因。

Genetic and molecular-biological investigations are proposed in order to determine whether a developmental compartment exists in the maize leaf. Previously, cell-lineage analyses and KNOX (markers of leaf/nonleaf identity) immunolocalizations of maize meristems indicated that a margin domain is not utilized in the leaf founder-cells of narrow sheath mutant plants. At maturity, narrow sheath mutant leaves are extremely narrow and devoid of specific cell and tissue types normally found at the edges of maize leaves. Together, these data indicate that a margin domain exists in the maize leaf and that this plant compartment may be established at the meristematic founder-cell stage via the activity of the duplicate genes narrow sheath1 and narrow sheath2. Three projects are proposed to test whether leaf margin development proceeds via the subdivision of founder-cells into distinct developmental domains or if the leaf margin is patterned much later in a non-compartmentalized manner.1) Clonal mosaic analysis will be used to infer the developmental timing and tissue-layer specificity of Ns2 gene function. This analysis will also determine if NS2 activity is confined to the margin domain of the leaf or is required in other leaf regions.2) Complete genomic and cDNA clones corresponding to each of the narrow sheath genes will be isolated and sequenced. Sequence analyses will reveal the degree of structural homology among nsl and ns2, and may suggest their molecular function.3) Northern analyses, RNA in situ hybridizations and immunohistolocalization assays of Ns gene expression throughout leaf development will test the hypothesis that the margins of maize leaves are patterned during the founder-cell stage of development by the domain-specific expression of the Ns genes.