Molecular Genetic Dissection of Red/Far-Red Light Signaling Pathways in Maize

最近对模式植物拟南芥的研究极大地扩展了我们对复杂的光信号转导网络的理解，这些光信号转导网络介导了一系列发育和环境响应。然而，随着拟南芥研究的快速进展，我们对远缘单子叶植物这一复杂途径的了解还远远不够完整。光敏色素基因家族组织、植物生理和选择压力的差异可能是导致拟南芥等高等真叶植物与玉米等单子叶禾草之间光信号转导途径不同的原因之一。这个项目的目标是利用经典和反向遗传学策略、分子遗传分析和微阵列技术开始详细描述玉米的红光/远红光信号通路。对玉米光敏色素基因家族结构和表达的全面分析是分析玉米光信号转导途径的重要基础。通过由NSF和政府资助的基因组学倡议开发的工具，已经在玉米的三个光敏色素基因家族成员中的两个成员中识别出转座子标记的等位基因。这些突变体的遗传和分子特征将包括使用微阵列技术比较野生型和这些PhyA和PhyB突变体在一系列光照条件下的核和叶绿体基因表达谱。最后，红光/远红光反应将在美国、加拿大、欧洲和南美的80份最能代表玉米种质多样性的核心材料中进行检验。这些研究应该为了解调节玉米光反应的潜在遗传多样性提供洞察力。

Recent studies in the model plant Arabidopsis thaliana have greatly expanded our understanding of the complex light signal transduction networks mediating a range of developmental and environmental responses. However, as studies rapidly progress in Arabidopsis, our knowledge of this complex pathway in the distantly related monocots is far less complete. Differences in phytochrome gene family organization, plant physiology and selection pressures have likely contributed to the divergence of light signal transduction pathways between higher eudicots such as Arabidopsis thaliana and monocotyledonous grasses such as Zea mays. The goal of this project is to begin the detailed characterization of red/far-red light signaling pathways in maize utilizing classical and reverse genetics strategies, molecular genetic analyses and microarray technologies. A comprehensive analysis of phytochrome gene family structure and expression in maize will be conducted as an important first step in the analysis of light signaling pathways in maize. Through tools developed by NSF- and government-funding genomics initiatives, transposon-tagged alleles have been identified in two of the three phytochrome gene family members in maize. Genetic and molecular characterizations of these mutants will include the use of microarray technology to compare nuclear and chloroplast gene expression profiles in wild type and these phyA and phyB mutants under a range of light conditions. Finally, red/far-red light responses will be examined in a core set of 80 US, Canadian, European, and South American accessions that best represent diversity in the maize germplasm pool. These studies should provide insights into the underlying genetic diversity regulating light responses in maize.