Auxin-regulated Organ-and Tissue-Specific Gene Expression

生长素调节的器官和组织特异性基因表达

• 批准号: 8904493
• 负责人: Thomas Guilfoyle
• 金额: $ 28万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-02-15 至 1993-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8904493&HistoricalAwards=false
• 关键词: Auxin; regulated; Organ; Tissue; Specific

The plant hormone, indoleacetic acid, appears to play key roles in regulating or inducing growth and developmental processes such as cell division, elongation, and differentiation. Exogenous application of this hormone or its synthetic analogs results in rapid changes in gene expression in seedlings or organs that are induced to undergo cell division or elongation. Dr. Guilfoyle has described a variety of auxin-induced mRNAs, and some of these, the SAUR of Small Auxin Up-regulated RNAs, are most abundant and most inducible in elongating regions of soybean hypocotyls. "Tissue printing" and in situ hybridization have been used to show that the SAUR genes are expressed primarily in epidermal and cortical cells of the elongating hypocotyl region, and furthermore, the mRNAs rapidly redistribute within the upper and lower portions of a gravistimulated soybean hypocotyl. The abundance of these small RNAs increases within 2.5 minutes after auxin application to elongating soybean hypocotyl sections, and half maximal steady state levels of these mRNAs are reached within 10 minutes after auxin administration. Dr. Guilfoyle has shown that the increase in RNA abundance after auxin addition results, at least in part, from increased transcription rates on the SAUR genes. On the other hand, an increase in RNA abundance after cycloheximide administration does not involve transcriptional activation, suggesting that post transcriptional events such as RNA stabilization may be involved. Recent results indicate that the SAUR genes are clustered within the soybean nuclear genome, and that the soybean genes are induced by auxin addition when the entire gene cluster is transferred via Agrobacterium T-DNA to petunia plats. Dr. Guilfoyle now proposes to 1) identify the cis-acting elements that confer auxin inducibility to the SAUR genes, 2) isolate, purify, and characterize trans acting factors that interact with the cis acting elements, 3) identify the cis acting elements that regulate the rapid turnover of the SAUR RNAs, 4) determine the patterns of auxin and gravity induced gene expression at the tissue, cellular, and subcellular levels using hybridization and immunological approaches, and 5) examine dwarf and gravitropic mutants for possible altered expression patterns of the SAUR genes and the phenotypes of transgenic plants which overproduce or underproduce the auxin induced RNAs. %%% The long range objectives of the proposed research are aimed at providing insight into how auxin activates specific genes in specific tissues, what proteins mediate the auxin induced gene activation, and what roles the auxin-induced gene products play in plant growth and development.

植物激素吲哚乙酸似乎在调节或诱导生长和发育过程（如细胞分裂、伸长和分化）中发挥着关键作用。外源应用这种激素或其合成类似物会导致幼苗或器官中基因表达的快速变化，从而诱导细胞分裂或伸长。 Guilfoyle 博士描述了多种生长素诱导的 mRNA，其中一些，即小生长素上调 RNA 的 SAUR，在大豆下胚轴的伸长区域中含量最丰富且最易诱导。 “组织印刷”和原位杂交已被用来表明SAUR基因主要在伸长的下胚轴区域的表皮和皮质细胞中表达，此外，mRNA在重力刺激的大豆下胚轴的上部和下部内快速重新分布。在将生长素施加到伸长的大豆下胚轴切片后2.5分钟内，这些小RNA的丰度增加，并且在施用生长素后10分钟内，这些mRNA的最大稳态水平达到一半。 Guilfoyle 博士表明，添加生长素后 RNA 丰度的增加至少部分是由于 SAUR 基因转录率的增加。另一方面，放线菌酮给药后 RNA 丰度的增加并不涉及转录激活，这表明可能涉及 RNA 稳定等转录后事件。最近的结果表明，SAUR 基因聚集在大豆核基因组内，并且当整个基因簇通过农杆菌 T-DNA 转移到矮牵牛时，大豆基因是通过添加生长素诱导的。 Guilfoyle 博士现在建议 1) 鉴定赋予 SAUR 基因生长素诱导性的顺式作用元件，2) 分离、纯化和表征与顺式作用元件相互作用的反式作用元件，3) 鉴定调节 SAUR RNA 快速周转的顺式作用元件，4) 确定组织、细胞和组织中生长素和重力诱导的基因表达模式。 使用杂交和免疫学方法在亚细胞水平上进行检测，5) 检查矮化和向重力突变体中 SAUR 基因的表达模式可能发生的改变，以及过量产生或不足产生生长素诱导的 RNA 的转基因植物的表型。 %%% 拟议研究的长期目标旨在深入了解生长素如何激活特定组织中的特定基因，哪些蛋白质介导生长素诱导的基因激活，以及生长素诱导的基因产物在植物生长和发育中发挥什么作用。