Ecophysiology and genetic analysis of plant adaptation to soil metal contamination

土壤重金属含量过高可能严重威胁生态系统的可持续性。调节植物中金属积累和抗性的生理和遗传机制是复杂的。我们的理解植物对金属毒性的反应是穷人，尽管最近使用的高通量方法。这项研究计划将为关键的非模式植物物种（在生物修复中有用）如何科普高土壤金属水平提供新的见解。这四个部分（目标）解决了四个相关的问题：1）植物如何科普金属使用遗传和比较转录组分析; 2）细胞和细胞外的位置和转运蛋白参与; 3）响应于金属污染的胞嘧啶甲基化的水平和分布;和4）DNA甲基化和基因调控之间的联系，以应对金属毒性。 我们首先证明，为了科普金属：1）糖槭（银枫）排除了它们; 2）山杨（颤抖的白杨）、白桦（白色桦）和红栎（红橡树）积累了它们; 3）红槭（红枫）避免了它们。重要的是，我们完成并表征了B的第一个转录组。papyrifera中鉴定了6个镍抗性候选基因。最近，我们的特点是在属桦木抗镍水平基因转移。我们相信，结合的方法将提供最强大的方式来阐明植物：金属应对机制。A. rubrum、红毛菊A. saccharinum，B. B. papyrifera、P. tremuloides和Q. rubra，使用遗传分析，转录组测序和RT-qPCR将识别响应高镍（Ni）和铜（Cu）差异调节的功能基因集。将在加拿大和其他地方的其他植物中建立与镍/铜抗性相关的新基因的分布。荧光原位，蛋白质表征和电子显微镜技术将建立细胞和细胞外分布图，并澄清镍和铜的主要影响，并参与运输蛋白。甲基化敏感扩增多态性（MSAP）分析和亚硫酸氢盐测序将评估表观遗传学在植物：金属反应中的作用。不仅DNA甲基化和基因表达之间的相关性，在甲基化组/转录组规模，而且DNA甲基化和调控的基因响应镍/铜污染之间的联系，将建立。我们的研究计划将有助于了解重金属稳态是如何实现的，以及不同基因在不同物种中转运蛋白的运作中的作用，这些物种在金属转运蛋白和排除剂方面可能存在很大差异。我们实现的目标将解决几个基本的植物：金属相互作用的问题，直接适用于重要的生物工程或植物选择策略。在这一阶段，将培训六名研究生，四名本科生和暑期学生，以填补加拿大生物技术的空白。

High soil metal levels may seriously threaten ecosystem sustainability. Physiological and genetic mechanisms regulating metal accumulation and resistance in plants are complex. Our understanding of plant responses to metal toxicity is poor despite recent uses of high-throughput methods. This research program will provide new insights on how key non-model plant species (useful in bioremediation) cope with high soil metal levels. The four parts (objectives) address four linked issues: 1) how plants cope with metals using genetic and comparative transcriptome analyses; 2) the cellular and extracellular locations and the transport proteins involved; 3) the levels and distribution of cytosine methylation in response to metal contamination; and 4) the link between DNA methylation and gene regulation in response to metal toxicity. We first demonstrated that, to cope with metals: 1) Acer saccharinum (silver maple) excludes them; 2) Populus tremuloides (trembling aspen), Betula papyrifera (white birch), and Quercus rubra (red oak) accumulate them; and 3) Acer rubrum (red maple) avoids them. Importantly, we completed and characterized the first transcriptome of B. papyrifera and identified six candidate nickel resistance genes therein. Recently, we characterized horizontal gene transfer of nickel resistance in the Genus Betula. We believe combining approaches will provide the most robust way of elucidating plant:metal coping mechanisms. Comparative analysis of A. rubrum, A. saccharinum, B. papyrifera, P. tremuloides, and Q. rubra, using genetic analysis, transcriptome sequencing, and RT-qPCR will identify functional gene-sets differentially regulated in response to high nickel (Ni) and copper (Cu). Distribution of novel genes associated with Ni/Cu resistance in other plants in Canada and elsewhere will be established. Fluorescence in situ, protein characterization, and electron microscopy techniques will establish cellular and extracellular distribution maps and clarify the main effects of Ni and Cu and involved transport proteins. Methylation sensitive amplified polymorphism (MSAP) analysis and bisulfite sequencing will assess the role of epigenetics in plant:metal responses. Not only correlations between DNA methylation and gene expression at the methylome/transcriptome scale, but also the link between DNA methylation and regulation of gene response to Ni/Cu contamination, will be established. Our research program will help understanding of how heavy metal homeostasis is achieved, and the role of different genes, in the operation of transporters in different species that may differ greatly in metal accumulators and excluders. Our achieved goals will address several fundamental plant:metal interaction issues directly applicable to important bioengineering or plant selection strategies. Six graduate, four undergraduate, and summer students will be trained, to fill this void in biotechnology in Canada, in this phase.