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

有大量证据表明，与植物生长所需的资源相比，防御的代谢成本要大得多。杨树中丰富的酚苷（PG）来源于水杨酸，水杨酸是草本和木本植物防御的核心代谢物，但其积累对草本植物的生长是非常昂贵的。通过研究一系列杂交和转基因杨树中PG调控的功能基因组学，我们希望了解这些植物如何适应如此昂贵的支出，并确定潜在的农业重要性基因。利用叶片PG含量和生长差异较大的棉杨杂交种，可以获得差异表达的PG调节基因和PG敏感基因。利用限氮和施用茉莉酸甲酯等诱导处理干扰杂交杨树和转基因杨树的PG稳态，验证基因功能并评估PG-生长相互作用。从这项工作中获得的EST序列和微阵列基因表达谱将存储在GenBank中，并可在www.aspenDB.mtu.edu上访问。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在项目网站aspenDB.mtu.edu上公布。项目研究结果将特别与了解可再生资源中光合作用利用效率的NPGI目标有关。预计会有几个更广泛的影响。杨树作为一种重要的生态物种，其生产力和植物化学对全球大气污染物和温室气体的变化特别敏感，深入了解树木碳收支的分子基础对进一步研究具有重要意义。由于PG和缩合单宁（CT）调节之间可能存在相互作用，以及CT对饲料消化率/品质的影响，因此对农业作物也有影响。杨树作为连接功能基因组学和生态研究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，因此在计划中的K-12教育活动中使用白杨尤为重要。计划的外展活动将强调基础研究对参与的学生及其家庭的重要性和价值。

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.