A Functional Genomics Approach to Investigate Regulation of Phenolic Glycoside Metabolism in Populus

有大量的证据表明，与植物生长所需的资源相比，防御的代谢成本很大。 杨属树种中丰富的酚苷（PG）来源于水杨酸，水杨酸是草本和木本植物物种防御的核心代谢物，但其积累对草本植物生长极其昂贵。 通过研究PG调节的功能基因组学在一系列的杂交和转基因杨树，我们希望了解这些植物如何适应这种昂贵的支出，并确定潜在的农业重要性的基因。 利用叶片PG含量和生长差异较大的棉白杨杂种，获得差异表达的PG调控基因和PG敏感基因。 PG诱导处理，包括氮限制和甲基-茉莉酸的应用将被用来扰乱PG稳态的杂交种，以及在转基因修饰的白杨，并验证基因功能和评估PG生长的相互作用。 从这项工作中获得的EST序列和微阵列基因表达谱将保存在GenBank中，并可在www.aspenDB.mtu.edu上查阅。cDNA微阵列也将提供给研究界。 有关EST、阵列和其他生物资源的发布时间表和费用结构的信息将公布在项目网站aspenDB.mtu.edu上。 项目结果将对NPGI了解可再生资源中光合作用利用效率的目标具有特别的相关性。深入了解树木碳预算的分子基础，应该是有价值的正在进行的调查，杨树作为关键生态物种的生产力和植物化学是特别敏感的全球变化，大气污染物和温室气体。 由于PG和缩合单宁（CT）调节之间可能的相互作用，以及CT对饲料消化率/质量的影响，也有农业作物的影响。杨树作为将功能基因组学与生态研究联系起来的模式生物的价值将在第4年通过针对树木生理学家和生态生理学家的专业微阵列研讨会进行传播。由于白杨对区域经济很重要，因此在计划的K-12教育活动中使用白杨特别重要。计划中的推广活动将向参与的学生及其家庭强调基础研究的重要性和价值。

There is a wealth of evidence that the metabolic cost of defense is large in comparison to resources available for growth in plants. The abundant phenolic glycosides (PG) of Populus tree species are derived from salicylic acid, a metabolite that is central to the defense of herbaceous and woody plant species, but whose accumulation is extremely costly to herbaceous plant growth. By investigating the functional genomics of PG regulation in a range of hybrid and transgenic Populus, we expect to learn how these plants accommodate such costly outlays, and to identify genes of potential agricultural importance. Cottonwood hybrids varying widely in leaf PG content and growth will be used to obtain differentially expressed PG-regulating and PG-sensitive genes. PG inductive treatments including nitrogen limitation and methyl-jasmonate application will be used to perturb PG homeostasis in the hybrids as well as in transgenically modified aspen, and to verify gene function and assess PG-growth interactions. EST sequences and microarray gene expression profiles derived from this work will be deposited in GenBank and accessible at www.aspenDB.mtu.edu. cDNA microarrays will also be made available to the research community. Information about the release schedule and fee structure of ESTs, arrays, and other biological resources will be posted on the project website at aspenDB.mtu.edu. Project findings will bear particular relevance to the NPGI goal of understanding efficiency of photosynthate utilization in a renewable resource.There are several anticipated broader impacts. A deeper understanding of the molecular basis of tree carbon budgeting should be of value to ongoing investigation of Populus as keystone ecological species whose productivity and phytochemisty is particularly sensitive to global changes in atmospheric pollutants and greenhouse gases. There are also agricultural crop implications due to possible interplay between PG and condensed tannin (CT) regulation, and the effects of CT on forage digestibility/quality. The value of Populus as a model organism for linking functional genomics to ecological research will be disseminated via a professional microarray workshop targeting tree physiologists and ecophysiologists in year 4. Because aspen is important to the regional economy its use in the planned K-12 educational activities is particularly relevant. Planned outreach activities will emphasize the significance and value of basic research to participating students and their families.